Solution:

10, 11, 12,………… 99

Now we need to find how many terms from this sequence are divisible by 13

The first two digit number divisible by 13 is 13; the next two digits number divisible by 13 is 26 and 39 so on. The last two digit numbers which are divisible by 13 is 91.

13 , 26, 39, …………….. 91

Now we need to find how many terms are there in this sequence for that let us use formula for n.

n = [(L-a)/d] + 1

a = 13 d = 26 – 13 L = 91

d = 13

n = [(91 - 13)/13] + 1

n = (78/13) + 1

n = 6 + 1

n = 7

7 two digit numbers are divisible by 13.