To highlight numbers that are multiples of a another number with conditional formatting, you can use a simple formula based on the MOD function.
In the example shown, the formula used to highlight multiples of 9 is...

To convert a time from one time zone to another, you can use a formula that converts hours entered as whole numbers to the decimal values that Excel recognizes as times. In the example shown, the formula in F5 is:
=...

To convert a measurement in inches to inches and feet (i.e. 53 to 4' 5") you can use a formula based on the INT and MOD functions. In the example shown, the formula in D5 is:
=INT(B5/12)&"' "&MOD(B5,...

If you want to highlight every other row in a table (sometimes called zebra striping) with conditional formatting you can do so with a simple formula that uses either the ISEVEN or ISODD function. For example, if you...

To highlight numbers that are integers, you can use a simple formula based on the MOD function. In the example shown, conditional formatting has been applied to the range B4:G11 using this formula:
=MOD(B4,1)=0
Note...

To add a given number of hours to a time, you can add hours divided by 24, or use the TIME function.
In the example shown, the formula in D5 is:
=B5+(C5/24)
Note: make sure results are formatted as time.
How this...

To calculate work hours, taking into account break time that needs to be subtracted, you can use a formula based on the MOD function. MOD is used to handle start and end times that cross midnight. In the example shown,...

To allow only numbers in multiples of 100, you can use data validation with a custom formula based on the MOD function. In the example shown, the data validation applied to C5:C10 is:
=MOD(C5,100)=0
How this formula...

To add an ordinal suffix to a number (i.e. 1st, 2nd, 3rd, etc.) you can use a formula based on the CHOOSE function to assign the suffix.
In the example shown, the formula in C5 is:
=CHOOSE(B5,"st","nd...

To count cells that contain only odd numbers, you can use a formula based on the SUMPRODUCT function together with the MOD function.
In the example, the formula in cell E6 is:
=SUMPRODUCT(--(MOD(rng,2)=1))
This...

To get the number at a specific place value you can use a formula based on the MOD function. By place value, we mean hundred thousands, ten thousands, thousands, hundreds, tens, ones, etc.
In the example shown, the...

To calculate the number of hours between two times, you can use a formula that simply subtracts the start time from the end time. This is useful to calculate working time, calculate elapsed time, etc. However, when...

To repeat a fixed value every 3 months, you can use a formula based on the DATEDIF and MOD functions. In the example shown, the formula in C4, copied down, is:
=IF(B4>=start,(MOD(DATEDIF(start,B4,"m")+n,n...

If you want to find the most recent Wednesday, or Saturday, or Monday, given a specific start date, you can use a formula that uses the MOD function.
How the formula works
Formulas that use the concept of "day of week...

To get the max of every nth column, you can use an array formula based on the MAX, MOD, and COLUMN functions. In the example shown, the formula in M5 is:
=MAX(IF(MOD(COLUMN(B5:K5)-COLUMN(B5)+1,L5)=0,B5:K5))
Note:...