alleryA number is divisible by 3 if which of its sums is divisible by 3?
ASum of all its digits
BSum of two end digits
CIts last digit alone
DIts count of digits
Answer & Solution
Correct answer: A. Sum of all its digits
1. Add all digits of the number.
2. If the digit sum is divisible by 3, so is the number; e.g. 492 gives 15, and 492 / 3 = 164.
3. Looking only at the last digit works for 2 and 5, not 3.
_Source: Wikipedia, Divisibility rule, Divisibility by 3 or 9_
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