Question

how many 2digit no. s are divisible by 3

Answer 1

Hola there,


To find two digit no. divisible by 3

A.P. = 12, 15,.........99

a = 12

an = 99

d = 15 - 12 = 3

=> an = a + (n - 1)d

=> 99 = 12 + (n - 1)3

=> n - 1 = 87/3

=> n - 1 = 29

=> n = 30

So, 30 two digit no. are divisible by 3.

Hope this helps....:)

Answer 2

let .a.p be .......12, 15........99
first we have to find common difference that is d= a2-a1
=15-12
=3
we know that general formula
$an = a + (n - 1) \times d$
99=12+(n-1)×3
= 12+3n-3
=9+3n
99-9=3n
90/3=n
n= 30
there fore 30 numbers