Question

How to find total number of two digit even numbers in natural numbers?

Answer 1

Two digit even natural numbers are
10, 12, 14,......, 98
This is in Arithmetic Progression with
first term, T1 = 10
Last term, Tn = 98
Common difference, d = 2.
Number of terms is
$n = \frac{Tn - T1}{d} + 1 \\ = \frac{98 - 10}{2} + 1 = 45$