Question

The number 123456 is not divisible by ________.

• A. 2
• B. 3
• C. 6
• D. 5

Answer 1

The correct option is D 5

1) Test for 2
The number ends with 6.
$⟹$ 123456 is divisible by 2
[If a number ends with 0, 2, 4, 6 or 8, it is divisible by 2]

2) Test for 3
Sum of digits = 1 + 2 + 3 + 4 + 5 + 6 = 21 which is divisible by 3.
$⟹$ 123456 is divisible by 3
[If sum of digits of a number is divisible by 3, the number is divisible by 3]

3) Test for 6
123456 is divisible by 2 and 3
$⟹$ 123456 is divisible by 6.
[If a number is divisible by 2 and 3, it is divisible by 6]

4) Test for 5
The number doesn't end with 5 or 0.
$⟹$ 123456 is not divisible by 5
[If a number is divisible by 5, it ends with 5 or 0]