🌟 **Part 1: Introduce** 🌟

✨ **Definition:**
The ISNUMBER function in Microsoft Excel is a built-in logical function that checks whether a given value is numeric. It returns TRUE if the value is numeric and FALSE if the value is not numeric.

✨ **Purpose:**
The main purpose of the ISNUMBER function is to determine if a cell or value is a numeric value. It is commonly used with other logical functions to validate data and perform calculations based on the data type.

✨ **Syntax & Arguments:**

```
=ISNUMBER(value)
```

`value`

: This is the value or cell reference you want to check if it is numeric.

✨ **Explain the Arguments in the Function:**
The `value`

The argument is mandatory and represents the cell or value you want to check if it is numeric. The ISNUMBER function evaluates this value and returns TRUE if it is numeric and FALSE if not.

✨ **Return Value:**
The ISNUMBER function returns either TRUE or FALSE.

- TRUE: If the
`value`

is a numeric value. - FALSE: If the
`value`

is not a numeric value.

✨ **Remarks:**

- The ISNUMBER function treats numbers (both integers and decimals) as numeric values.
- It also considers logical (TRUE and FALSE) numeric values, where TRUE is equivalent to 1, and FALSE equals 0.
- Empty cells or cells containing Text, errors, or other non-numeric values are considered not numeric.

🌟 **Part 2: Examples** 🌟

1️⃣ **Example using ISNUMBER with IF and SUM:**

A | B | C | |
---|---|---|---|

1 | |||

2 | Value 1 | Value 2 | Sum Result |

3 | 100 | 150 | =IF(ISNUMBER(A3), SUM(A3:B3), “Invalid Input”) |

4 | “200” | ||

5 | “Not Num” | 50.5 |

**Explanation:**

- In this example, we have two columns of values: Value 1 (column A) and Value 2 (column B).
- In cell C3, we use the ISNUMBER function to check if the value in A3 (Value 1) is numeric.
- Since A3 contains the numeric value 100, the ISNUMBER function returns TRUE, and the IF function calculates the sum of A3:B3 using the SUM function.
- The sum of 100 and 150 is 250, so cell C3 displays 250.
- In cell C4, the ISNUMBER function returns FALSE again, and A4 contains the text “200” (a text representation of a number). However, the SUM function treats “200” as a number and returns 200 as the result in cell C4.
- In cell C5, both A5 and B5 are non-numeric values (Text and decimal), so the ISNUMBER function returns FALSE. The IF function displays “Invalid Input” to indicate that the input is not a valid numeric value.

2️⃣ **Example using ISNUMBER with IF and AVERAGE:**

A | B | C | |
---|---|---|---|

1 | |||

2 | Test 1 | Test 2 | Average Result |

3 | 90 | 85 | =IF(ISNUMBER(A3), AVERAGE(A3:B3), “Invalid Input”) |

4 | 75 | ||

5 | “80” | 75.5 |

**Explanation:**

- In this example, we have two columns of test scores: Test 1 (column A) and Test 2 (column B).
- In cell C3, we use the ISNUMBER function to check if the value in A3 (Test 1) is numeric.
- Since A3 contains the numeric value 90, the ISNUMBER function returns TRUE, and the IF function calculates the average of A3:B3 using the AVERAGE function.
- The average of 90 and 85 is 87.5, so cell C3 displays 87.5.
- In cell C4, the ISNUMBER function returns TRUE again, and A4 contains the numeric value 75. The AVERAGE function calculates the average of 75 and a blank cell, which is 75. Therefore, cell C4 displays 75.
- In cell C5, both A5 and B5 are non-integer values (Text and decimal), so the ISNUMBER function returns FALSE. The IF function displays “Invalid Input” to indicate that the input is not a valid numeric value.

3️⃣ **Example using ISNUMBER with IF and COUNTIF:**

A | B | C | |
---|---|---|---|

1 | |||

2 | Category | Amount | Count Result |

3 | “Food” | $50 | =IF(ISNUMBER(B3), COUNTIF(B3:B5, B3), “Invalid”) |

4 | “Travel” | ||

5 | 80 | $30 |

**Explanation:**

- This Example shows a table of expenses with their corresponding categories and amounts.
- In cell C3, we use the ISNUMBER function to check if the value in B3 (Amount) is numeric.
- Since B3 contains the numeric value $50, the ISNUMBER function returns TRUE, and the IF function counts the occurrences of $50 in the range B3:B5 using the COUNTIF function.
- The COUNTIF function returns 1, as there is one occurrence of $50 in B3, so cell C3 displays one as a result.
- In cell C4, the ISNUMBER function returns FALSE again, and there is no value for the category “Travel.” The IF function displays “Invalid” to indicate the absence of data.
- In cell C5, the ISNUMBER function returns TRUE again, and B5 contains the numeric value $30. The COUNTIF function counts the occurrences of $30 in the range B3:B5 and returns 1, and cell C5 displays 1.

4️⃣ **Example using ISNUMBER with IF and VLOOKUP:**

A | B | C | |
---|---|---|---|

1 | |||

2 | ID | Score | Result |

3 | 101 | 85 | =IF(ISNUMBER(VLOOKUP(A3, F3:G5, 2, FALSE)), “Found”, “Not Found”) |

4 | 102 | ||

5 | 103 | 90.5 | |

6 | 104 |

**Explanation:**

- This Example has a table with student IDs and their corresponding scores.
- In cell C3, we use the ISNUMBER function combined with VLOOKUP to check if the value in A3 (ID) is numeric and if it exists in the lookup range F3:G5.
- The VLOOKUP function searches for the value in A3 within the range F3:G5 and returns the corresponding score (85) since ID 101 is found. The ISNUMBER function confirms that the score is numeric, and the IF function displays “Found” in cell C3.
- In cell C4, the ISNUMBER function returns FALSE again, and there is no value for ID 102 in the lookup range. The VLOOKUP function returns an error, and the ISNUMBER function detects the error as non-numeric. The IF function displays “Not Found” in cell C4.
- In cell C5, the ISNUMBER function returns TRUE again, and the VLOOKUP function successfully finds the score (90.5) for ID 103. The IF function displays “Found” in cell C5.
- In cell C6, the ISNUMBER function returns FALSE again, and there is no value for ID 104 in the lookup range. The VLOOKUP function returns an error, and the ISNUMBER function detects the error as non-numeric. The IF function displays “Not Found” in cell C6.

5️⃣ **Example using ISNUMBER with IF and MAX:**

A | B | C | |
---|---|---|---|

1 | |||

2 | Value 1 | Value 2 | Max Result |

3 | 90 | 85 | =IF(ISNUMBER(A3), MAX(A3:B3), “Invalid Input”) |

4 | 75 | ||

5 | 80 | “75” |

**Explanation:**

- In this example, we have two columns of values: Value 1 (column A) and Value 2 (column B).
- In cell C3, we use the ISNUMBER function to check if the value in A3 (Value 1) is numeric.
- Since A3 contains the numeric value 90, the ISNUMBER function returns TRUE, and the IF function calculates the maximum value between A3 and B3 using the MAX function.
- The maximum value between 90 and 85 is 90, so cell C3 displays 90.
- In cell C4, the ISNUMBER function returns TRUE again, and A4 contains the numeric value 75. The MAX function calculates the maximum value between 75 and a blank cell, and the maximum is 75. Therefore, cell C4 displays 75.
- In cell C5, the ISNUMBER function returns FALSE once more, and B5 contains the text “75” (a text representation of a number). However, the MAX function treats “75” as a number and returns 75 as the result in cell C5.

6️⃣ **Example using ISNUMBER with IF and COUNTIF:**

A | B | C | |
---|---|---|---|

1 | |||

2 | Category | Amount | Count Result |

3 | “Food” | $50 | =IF(ISNUMBER(B3), COUNTIF(B3:B5, B3), “Invalid”) |

4 | “Travel” | ||

5 | 80 | $30 |

**Explanation:**

- This Example shows a table of expenses with their corresponding categories and amounts.
- In cell C3, we use the ISNUMBER function to check if the value in B3 (Amount) is numeric.
- Since B3 contains the numeric value $50, the ISNUMBER function returns TRUE, and the IF function counts the occurrences of $50 in the range B3:B5 using the COUNTIF function.
- The COUNTIF function returns 1, as there is one occurrence of $50 in B3, so cell C3 displays 1.
- In cell C4, the ISNUMBER function returns FALSE again, and there is no value for the category “Travel.” The IF function displays “Invalid” to indicate the absence of data.
- In cell C5, the ISNUMBER function returns TRUE again, and B5 contains the numeric value $30. The COUNTIF function counts the occurrences of $30 in the range B3:B5 and returns 1, and cell C5 displays 1.

7️⃣ **Example using ISNUMBER with IF and SUBSTITUTE:**

A | B | C | |
---|---|---|---|

1 | |||

2 | Text | Find | Result |

3 | Apple | “p” | =IF(ISNUMBER(A3), SUBSTITUTE(A3, B3, “Pine”), “”) |

4 | Orange | ||

5 | “Banana” | “a” |

**Explanation:**

- In this example, we have two columns: Text (column A) and Find (column B).
- In cell C3, we use the ISNUMBER function to check if the A3 (Text) value is numeric.
- Since A3 contains the text “Apple,” the ISNUMBER function returns FALSE, and the IF function proceeds to check if the letter “p” (B3) is found in the text “Apple.” The SUBSTITUTE function performs this check and returns the text “Apple” (no replacements made).
- In cell C4, the ISNUMBER function returns FALSE again, and A4 contains the text “Orange.” However, since B4 is blank, the SUBSTITUTE function performs no replacements, and cell C4 displays “Orange” unchanged.
- In cell C5, the ISNUMBER function returns TRUE once more, and A5 contains the text “Banana.” The SUBSTITUTE function replaces the letter “a” (B5) with “Pine” in “Banana” and returns “BpinepineNpine” as the result in cell C5.

8️⃣ **Example using ISNUMBER with IF and LEN:**

A | B | C | |
---|---|---|---|

1 | |||

2 | Text | Threshold | Result |

3 | “Excel” | 5 | =IF(ISNUMBER(B3), IF(LEN(A3)>B3, “Long”, “Short”), “Invalid Input”) |

4 | “Function” | ||

5 | “Sheet” | 6 |

**Explanation:**

- In this example, we have two columns: Text (column A) and Threshold (column B).
- In cell C3, we use the ISNUMBER function to check if the B3 (Threshold) value is numeric.
- Since B3 contains the numeric value 5, the ISNUMBER function returns TRUE, and the IF function proceeds to check if the text length in A3 (“Excel”) is greater than the threshold 5 using the LEN function.
- The LEN function calculates the length of “Excel” (5 characters), which is equal to the threshold, so cell C3 displays “Short” as a result.
- In cell C4, the ISNUMBER function returns TRUE again, and A4 contains the text “Function.” The LEN function calculates the length of “Function” (8 characters), which is greater than the threshold (5). Therefore, cell C4 displays “Long.”
- In cell C5, the ISNUMBER function returns TRUE once more, and A5 contains the text “Sheet.” The LEN function calculates the length of “Sheet” (5 characters), which is equal to the threshold, so cell C5 displays “Short.”

9️⃣ **Example using ISNUMBER with IF and CONCATENATE:**

A | B | C | |
---|---|---|---|

1 | |||

2 | FirstName | LastName | Full Name |

3 | “John” | “Doe” | =IF(ISNUMBER(A3), CONCATENATE(A3, ” “, B3), “Invalid Input”) |

4 | “Jane” | ||

5 | 25 | “Smith” |

**Explanation:**

- In this example, we have two columns: FirstName (column A) and LastName (column B).
- In cell C3, we use the ISNUMBER function to check if the value in A3 (FirstName) is numeric.
- Since A3 contains the text “John,” the ISNUMBER function returns FALSE, and the IF function displays “Invalid Input” in cell C3 since the first name should not be a numeric value.
- In cell C4, the ISNUMBER function returns TRUE again, and A4 contains the text “Jane.” The CONCATENATE function combines the FirstName “Jane” with a blank space and the LastName “Doe” to form the Full Name “Jane Doe,” and cell C4 displays “Jane Doe” as a result.
- In cell C5, the ISNUMBER function returns TRUE once more, and A5 contains the numeric value 25. The CONCATENATE function combines the numeric value 25 with a blank space and the last name “Smith” to form the Full Name “25 Smith,” and cell C5 displays “25 Smith” as a result.

🔟 **Example using ISNUMBER with IF and ROUND:**

A | B | C | |
---|---|---|---|

1 | |||

2 | Value | Decimals | Rounded Result |

3 | 3.456 | 2 | =IF(ISNUMBER(A3), ROUND(A3, B3), “Invalid”) |

4 | 7.892 | ||

5 | “12.789” | 1 |

**Explanation:**

- This Example has Values (column A) and Decimals (column B).
- In cell C3, we use the ISNUMBER function to check if the value in A3 (Value) is numeric.
- Since A3 contains the numeric value 3.456, the ISNUMBER function returns TRUE, and the IF function rounds the value in A3 to 2 decimals using the ROUND function.
- The rounded value of 3.456 to 2 decimals is 3.46, so cell C3 displays 3.46.
- In cell C4, the ISNUMBER function returns TRUE again, and A4 contains the numeric value 7.892. The ROUND function rounds the value in A4 to 0 decimals (no decimals specified in B4), resulting in 8. Therefore, cell C4 displays 8.
- In cell C5, the ISNUMBER function returns FALSE once more, and A5 contains the text “12.789” (a text representation of a number). The IF function displays “Invalid” in cell C5 because the value in A5 should be a numeric value for rounding.

1️⃣1️⃣ **Example using ISNUMBER with IF and LEFT:**

A | B | C | |
---|---|---|---|

1 | |||

2 | Text | NumChars | Result |

3 | “Excel” | 3 | =IF(ISNUMBER(A3), LEFT(A3, B3), “Invalid Input”) |

4 | “Function” | ||

5 | 75.5 | 2 |

**Explanation:**

- In this example, we have two columns: Text (column A) and NumChars (column B).
- In cell C3, we use the ISNUMBER function to check if the A3 (Text) value is numeric.
- Since A3 contains the text “Excel,” the ISNUMBER function returns FALSE, and the IF function displays “Invalid Input” in cell C3 since the Text should not be a numeric value.
- In cell C4, the ISNUMBER function returns TRUE again, and A4 contains the text “Function.” The LEFT function extracts the leftmost 3 characters from “Function,” resulting in “Fun,” and cell C4 displays “Fun” as the result.
- In cell C5, the ISNUMBER function returns FALSE once more, and A5 contains the numeric value 75.5. The IF function displays “Invalid Input” in cell C5 since the Text should be a text value for the LEFT function.

1️⃣2️⃣ **Example using ISNUMBER with IF and AVERAGEIF:**

A | B | C | |
---|---|---|---|

1 | |||

2 | Category | Amount | Average Result |

3 | “Food” | $50 | =IF(ISNUMBER(B3), AVERAGEIF(B3:B5, B3, B3:B5), “”) |

4 | “Travel” | ||

5 | 80 | $30 |

**Explanation:**

- This Example shows a table of expenses with their corresponding categories and amounts.
- In cell C3, we use the ISNUMBER function to check if the value in B3 (Amount) is numeric.
- Since B3 contains the numeric value $50, the ISNUMBER function returns TRUE, and the IF function calculates the average of amounts that match the value $50 (Food) in the range B3:B5 using the AVERAGEIF function.
- The AVERAGEIF function calculates the average of $50 and $30 ($50 + $30) / 2 = $40, so cell C3 displays $40.
- In cell C4, the ISNUMBER function returns TRUE again, and there is no value for the category “Travel.” The AVERAGEIF function cannot find matching amounts, so cell C4 displays a blank cell.
- In cell C5, the ISNUMBER function returns TRUE once more, and B5 contains the numeric value $30. The AVERAGEIF function calculates the average of $30 and $50, which is ($50 + $30) / 2 = $40, so cell C5 displays $40.

🌟 **Part 3: Tips and Tricks** 🌟

- The ISNUMBER function is proper when dealing with large datasets where you must validate whether specific cells contain numeric values.
- It can be combined with other functions, such as IF, SUM, AVERAGE, COUNTIF, etc., to perform data calculations based on the data type.
- Be cautious when working with data imported from external sources, as sometimes numeric values can be formatted as Text, leading to incorrect results when using the ISNUMBER function.
- To ensure accurate results, use the VALUE function to convert text-formatted numbers to actual numeric values before applying the ISNUMBER function. For Example,
`=ISNUMBER(VALUE(A1))`

. - Remember to handle any errors that may arise when using the ISNUMBER function, such as dividing by zero or dealing with invalid data, to avoid unexpected results.