Question

Which of the following is divisible by 3?

• A. $12$
• B. $51$
• C. $81$
• D. All the above

Answer 1

The correct option is D

All the above

Determine the number which is divisible by 3.

Divisibility rule of 3: A number is completely divisible by 3 if the sum of its digits is divisible by 3.

For point A)

Given number $=12$

$$\begin{gathered} 12=1+2 \\ \Rightarrow =3nowcheckDivisibility3 \\ \Rightarrow =\frac{3}{3} \\ \Rightarrow =1 \end{gathered}$$

here, $12$ is divisible by $3$.

For point B)

Given number $=51$

$$\begin{gathered} 51=5+1 \\ \Rightarrow =6nowcheckDivisibility3 \\ \Rightarrow =\frac{6}{3} \\ \Rightarrow =2 \end{gathered}$$

here, $51$ is divisible by $3$.

For point C)

Given number $=81$

$$\begin{gathered} 81=8+1 \\ \Rightarrow =9nowcheckDivisibility3 \\ \Rightarrow =\frac{9}{3} \\ \Rightarrow =3 \end{gathered}$$

here, $81$ is divisible by $3$.

Hence, the correct choice is “Option D”.