1. Excel ISERROR Function

2. Excel ISERROR Function
Purpose 
Test for any error
Return value 
A logical value (TRUE or FALSE)
Syntax 
=ISERROR (value)
Arguments 
value - The value to check for any error.

3. Excel ISERROR Function
Usage notes 
Use the ISERROR function to see if a cell contains any error message, including #N/A, #VALUE!, #REF!, #DIV/0!, #NUM!, #NAME?, or #NULL!
For example, =ISERROR(A1) will return TRUE if A1 is displaying an one of the errors mentioned above , and FALSE if not.
Frequently, value is supplied as a cell address, but you can use it to trap errors inside more complex formulas as well.

4. Excel ISERROR Function

5. Excel ISEVEN Function

6. Excel ISEVEN Function Purpose Test if a value is even Return value
A logical value (TRUE or FALSE)
Syntax 
=ISEVEN (value)
Arguments 
value - The numeric value to check.

7. Excel ISEVEN Function Usage notes
Use the ISEVEN function to check if a numeric value is an even number. ISEVEN will return TRUE when a numeric value is even and FALSE when a numeric value is odd. If value is not numeric, ISEVEN will return the #VALUE error.
For example, =ISEVEN(A1) will return TRUE if A1 contains the number 2 and FALSE if A1 contains the number 3.
Usually, value is supplied as a cell address.
ISEVEN is part of a group of functions called the IS functions that all return the logical values TRUE or FALSE.

8. Excel ISFORMULA Function

9. Excel ISFORMULA Function
Purpose 
Test if cell contains a formula
Return value 
TRUE or FALSE
Syntax 
=ISFORMULA (reference)
Arguments 
reference - Reference to cell or cell range.

10. Excel ISFORMULA Function
Usage notes 
You can use the ISFORMULA function to test a cell to see if it contains a formula. ISFORMULA returns TRUE when a cell contains a formula and FALSE if not.
Remember that you can temporarily display all formulas in a worksheet with a keyboard shortcut.
To extract and display a formula, use the FORMULATEXT function.
Notes:
ISFORMULA was introduced in Excel 2013.

11. Excel ISFORMULA Function

12. Excel ISLOGICAL Function

13. Excel ISLOGICAL Function
Purpose 
Test if a value is logical
Return value 
A logical value (TRUE or FALSE)
Syntax 
=ISLOGICAL (value)
Arguments 
value - The value to test as logical.

14. Excel ISLOGICAL Function
Usage notes 
Use the ISLOGICAL function to check if a value is logical. ISLOGICAL will return TRUE when a value is TRUE or FALSE.
For example, =ISERROR(A1) will return TRUE if A1 contains either TRUE or FALSE.
Note that 1 and 0 (zero) are not evaluated as TRUE and FALSE. However, you can use the AND function to evaluate 1 and 0 and TRUE and FALSE.
Normally, value is supplied as a cell address.
ISLOGICAL is part of a group of functions called the IS functions, which are often used to test the result of formulas for errors.

15. Excel ISNA Function

16. Excel ISNA Function Purpose Test for the #N/A error Return value
A logical value (TRUE or FALSE)
Syntax 
=ISNA (value)
Arguments 
value - The value to check if #N/A.

17. Excel ISNA Function Usage notes
Use the ISNA function to check if a value is #N/A. ISNA will return TRUE when value is #N/A
For example, =ISNA(A1) will return TRUE if A1 contains #N/A.
Normally, value is supplied as a cell address.
ISNA is part of a group of functions called the "IS functions", which are often used to test the result of formulas for errors.

18. Excel ISNONTEXT Function

19. Excel ISNONTEXT Function
Purpose 
Test for a non-text value
Return value 
A logical value (TRUE or FALSE)
Syntax 
=ISNONTEXT (value)
Arguments 
value - The value to check.

20. Excel ISNONTEXT Function
Usage notes 
Use the ISNONTEXT function to check if a value is not text. ISNA will return TRUE when value is a non-text value.
For example, =ISNA(A1) will return TRUE if A1 contains a number or a formula.
Note that ISNONTEXT will also return TRUE for blank cells.
Often, value is supplied as a cell address.
ISNONTEXT is part of a group of functions called the IS functions that return the logical values TRUE or FALSE.

21. Excel ISNUMBER Function

22. Excel ISNUMBER Function
Purpose 
Test for numeric value
Return value 
A logical value (TRUE or FALSE)
Syntax 
=ISNUMBER (value)
Arguments 
value - The value to check.

23. Excel ISNUMBER Function
Usage notes 
Use the ISNUMBER function to check if a value is a number. ISNUMBER will return TRUE when value is numeric and FALSE when not.
For example, =ISNUMBER(A1) will return TRUE if A1 contains a number or a formula that returns a numeric value. If A1 contains text, ISNUMBER will return FALSE.
Normally, value is supplied as a cell address.
ISNUMBER is part of a group of functions called the IS functions.

24. Excel ISODD Function

25. Excel ISODD Function Purpose Test if a value is odd Return value
A logical value (TRUE or FALSE)
Syntax 
=ISODD (value)
Arguments 
value - The numeric value to check.

26. Excel ISODD Function Usage notes
Use the ISODD function to check if a numeric value is an odd number. ISODD will return TRUE when a numeric value is odd and FALSE when a numeric value is even. If value is not numeric, ISODD will return the #VALUE error.
For example, =ISODD(A1) will return TRUE if A1 contains the number 3 and FALSE if A1 contains the number 4.
Usually, value is supplied as a cell address.
ISODD is part of a group of functions called the IS functions that all return the logical values TRUE or FALSE.

27. Excel ISREF Function

28. Excel ISREF Function Purpose Test for a reference Return value
A logical value (TRUE or FALSE)
Syntax 
=ISREF (value)
Arguments 
value - The value to check.

29. Excel ISREF Function Usage notes
Use the ISREF function to check if value is a reference. ISREF will return TRUE when value is a reference and FALSE if not.
For example, =ISREF(A1) will return TRUE and =ISREF("apple") will return false.
ISREF is part of a group of functions called the IS functions that all return the logical values TRUE or FALSE.

30. Excel ISTEXT Function

31. Excel ISTEXT Function Purpose Test for a text value Return value
A logical value (TRUE or FALSE)
Syntax 
=ISTEXT (value)
Arguments 
value - The value to check.

32. Excel ISTEXT Function Usage notes
Use the ISTEXT function to check if value is text. ISTEXT will return TRUE when value is text.
For example, =ISTEXT(A1) will return TRUE if A1 contains "apple".
Often, value is supplied as a cell address.
ISTEXT is part of a group of functions called the IS functions that return the logical values TRUE or FALSE.

33. Excel N Function

34. Excel N Function Purpose Convert a value to a number Return value
A number or error code
Syntax 
=N (value)
Arguments 
value - The value to convert to a number.
Usage notes 
Use the N function to convert value to a number. Values are converted according the following table:
Input value
Return value
Any number
Same number
A recognized date
A date in Excel serial number format
TRUE 1
FALSE
An error code (#VALUE, #N/A, etc)
Same error code
Other values

35. Excel N Function
In most cases, using the N function is unnecessary, because Excel automatically converts values when needed.
The N function is provided for compatibility with other spreadsheet programs.
Note: you should know there is a tricky use of N() that allows you to use it as a way to leave in-cell comments. The technique:  add a plus sign at the end of your formula with a comment as text in quotes inside the N() function like so:
=SUM(A1:A10) + N("This is my comment about this SUM function")
When you click on that cell, you'll see both the formula and the comment in the formula bar. The N() function has no impact on the result of the function. In fact, you can add more than one N() function to a formula to annotate other functions, constants, or both.

36. Excel NA Function

37. Excel NA Function Purpose Return value Syntax Usage notes
Create an #N/A error
Return value 
The #N/A error
Syntax 
=NA ()
Usage notes 
Use NA to generate the #N/A. #N/A means "not available" or "no value available". For example, you can use NA to flag cells that are empty or missing information.
When other formulas refer to cells that contain #N/A, the also return #N/A.
NA takes no arguments, but you must provide empty parentheses.
You can also enter the value #N/A directly into a cell.

38. Excel TYPE Function

39. Excel TYPE Function Usage notes Purpose
Get the type of value in a cell
Return value 
A numeric code representing type
Syntax 
=TYPE (value)
Arguments 
value - The value to check the type of.
Usage notes 
Use TYPE to test the value in a particular cell so that other functions that depend on the type can perform as expected.

40. Excel TYPE Function
You can use TYPE to find out the type of data that is returned by a function or formula.
You can't use TYPE to test for a formula, because TYPE evaluates the result of formulas and functions.
The table below shows the possible type codes returned from TYPE and the meaning of each:
Type code
Meaning 1
Number 2
Text 4
Logical value 16
Error value 64
Array

41. Excel AND Function

42. Excel And Function Purpose Test multiple conditions with AND
Return value 
TRUE if all arguments evaluate TRUE; FALSE if not
Syntax 
=AND (logical1, [logical2], ...)
Arguments 
logical1 - The first condition or logical value to evaluate.
logical2 - [optional] The second condition or logical value to evaluate.

43. Excel And Function Usage notes
Use the AND function to test multiple conditions at the same time, up to 255 conditions. Each logical condition (logical1, logical2, etc.) must evaluate to TRUE or FALSE, or be arrays or references that contain logical values.
For example, to test if the value in A1 is greater than 0 and less than 5, use the following formula:
=AND(A1>0,A1<5)
It can be useful to extend the functionality of functions like IF with AND. Using the above example, you can supply AND as the logicaltest for the IF function like so:
=IF(AND(A1>0,A1<5), "Approved", "Denied")
This formula will return "Approved" only if the value in A1 is greater than 0 and less than 5.
Notes:
Text values or empty cells supplied as arguments are ignored.
The AND function will return #VALUE if no logical values are found or created during evaluation.

44. Excel And Function

45. Excel FALSE Function

46. Excel FALSE Function Purpose Return value Syntax Usage notes
Generate the logical value FALSE
Return value 
The logical value FALSE
Syntax 
=FALSE ()
Usage notes 
The FALSE function takes no arguments. Use FALSE to generate the logical value FALSE. For example, to return FALSE if the value in A1 < 0, use the formula:
=IF(A1<0, FALSE())

47. Excel FALSE Function
Note that you can also just use enter the word FALSE directly into a cell or formula and Excel will interpret this as the logical value FALSE. For example, these formulas are functionally identical:
=IF(A1<0, FALSE())
=IF(A1<0, FALSE)
Both formulas return FALSE if the value in A1 < 0.
Microsoft states that the FALSE function is provided mainly for compatibility with other spreadsheet applications.