Question

How many two-digit numbers are divisible by $3$ ?

• A. $25$
• B. $27$
• C. $30$
• D. $33$

Answer 1

Answer: (C)

$30$

Two digit numbers divisible by $3$ are $12,15,18,.........,99$

$\Rightarrow a=12,d=3,l=99$

$\Rightarrow a_n=a+(n-1)d$
$\Rightarrow 99=12+(n-1)3$
$\Rightarrow 99=12+3n-3$
$\Rightarrow 99=3n+9$
$\Rightarrow 3n=90$
$\Rightarrow n=30$