Is 728 divisible by 8

Answer 1

To determine if 728 is divisible by 8, we need to check if 8 is a factor of 728. To do this, we divide 728 by 8. If the division results in a whole number without any remainder, then 728 is divisible by 8. In this case, 728 ÷ 8 = 91, so yes, 728 is divisible by 8.

Answer 2

To check for divisibility by 8 add four times the hundreds digit to twice the tens digit to the units digit; if this sum is divisible by 8 then so is the original number:

For 728: 4×7 + 2×2 + 8 = 40 which is divisible by 8, so 728 is divisible by 8.

The test can be repeated on the sum, so if the test is repeatedly applied to the sums until a single digit remains, only if this single digit is 8 then the original number is divisible by 8 (otherwise the excess of this number over a multiple of 8 is the remainder when the original number is divided by 8, ie if it is less than 8 it is the remainder, else it is 9 and the remainder is 9 - 8 = 1).

For 728: 4×7 + 2×2 + 8= 40

40: 4×0 + 2×4 + 0 = 8

This single digit is 8, so 728 is divisible by 8.