How many two - digit numbers are divisible by 6?
The two digit numbers divisible by 6 are 12, 18, 24, 30,…96.
This forms an AP with first term a = 12
and common difference = d = 6
Last term is 96.
Now, number of terms in this AP are given as:
96 = a + (n - 1)d
⇒ 96 = 12 + (n - 1)6
⇒ 96 - 12 = 6n - 6
⇒ 84 + 6 = 6n
⇒ 90 = 6n
⇒ n = 15
There are 15 two - digit numbers that are divisible by 6.