Which of these numbers is not divisible by 3? Choices.
A) 339 B) 342 C) 552 D) 1111 E) 672
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= 
<gadget id="calculator">3 + 3 + 9</gadget>
<output>15</output>
15 , divisible by 3.   3 + 4 + 2= 
<gadget id="calculator">3 + 4 + 2</gadget>
<output>9</output>
9 , divisible by 3.   5 + 5 + 2= 
<gadget id="calculator">5 + 5 + 2</gadget>
<output>12</output>
12 , divisible by 3.   1 + 1 + 1 + 1= 
<gadget id="calculator">1 + 1 + 1 + 1</gadget>
<output>4</output>
4 , not divisible by 3.   The number 1111 is not divisible by 3 the answer is 1111.
<result>D</result>
Which of these numbers is not divisible by 3?