Question

Which of the following numbers is divisible by 33 ?

• A. 1333
• B. 2145
• C. 2133
• D. 1375

Answer 1

Answer:

B. 2145

To find the number divisible by 33, it must be divisible by both 3 and 11 ($3 \times 11 = 33$).

## 1. Test for 3 (Sum of digits must divide by 3)

* 1333 $\rightarrow 1+3+3+3 = 10$

* 1375 $\rightarrow 1+3+7+5 = 16$

* 2133 $\rightarrow 2+1+3+3 = 9$ (Divisible by 3)

* 2145 $\rightarrow 2+1+4+5 = 12$ (Divisible by 3)

## 2. Test remaining numbers for 11

Check 2145 by subtracting alternating digits:

$(2 + 4) - (1 + 5) = 6 - 6 = \mathbf{0}$Since the result is 0, it is divisible by 11.

Answer: 2145 is the correct option.