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.