Mathematics Math Shortcuts Math Shortcut to Tell if a Number is Divisible by 4
Written by Andrew B. Bartels, October 2011
Rule for Division by 4:
A number is evenly divisible by 4 if the double of the tens digit plus the ones digit is evenly divisible by 4.
Example 1:
Number: 580
The last two digits are: 8 and 0
(8 * 2) + 0 = 16
The computed total from doubling the tens value (8) added to the ones digit (0) is 16, which is evenly divisible by 4 (the answer is 4), therefore 580 is evenly divisible by 4 (the answer is 145)
Example 2:
Number: 642
The last two digits are: 4 and 2
(4 * 2) + 2 = 10
The computed total from doubling the tens value (4) added to the ones digit (2) is 10, which is not evenly divisible by 4 (the answer is 2.5), therefore 642 is not evenly divisible by 4 (the answer is 160.5)
Example 3:
Number: 4456
The last two digits are: 5 and 6
(5 * 2) + 6 = 16
The computed total from doubling the tens value (5) added to the ones digit (6) is 16, which is evenly divisible by 4 (the answer is 4), therefore 4456 is evenly divisible by 4 (the answer is 1114)
