Question

Which of these numbers is not divisible by 3 ?
A) 339
C) 552
D) 1111

Answer 1

Solution
One may answer this question using a calculator and test for divisibility by $3.$
However we can also test for divisibilty by adding the digits and if the result is divisible by3 then the number is divisible by $3.$
$3+3+9=15$, divisible by 3
$5+5+2=12$, divisible by 3
$1+1+1+1=4$, not divisible by 3 .
The number 1111 is not divisible by 3 the answer is $C$.
Answer: C