Question

how many two digit no. are divisible by 3??​

Answer 1

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30

An arithmetic progression (A.P) is a progression in which the difference between two consecutive terms is constant. ∴ Two digit numbers divisible by 3 = 30.

Answer 2

Answer:

The two digit numbers which are divisible by 3 are:-

12,15,18.. . .. .. .. .. .99

This is an A.P. of common difference, d = 3

first term, a = 12 , last term, l = 99

So, we have to find number of terms:

$l = a + (n - 1)d$

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

$= > 99 + 12 + 3n - 3$

$= > 99 = 9 + 3n$

$= >9 + 3n = 99$

$= > 3n = 99 - 9$

$= > 3n = 90$

$= > n = \frac{90}{3}$

$so ,\: n \: = 30$

hence, there are 30 numbers of two digits which are divisible by 3.