sir i want to ask that if in exam i got to find al even numbere from 100 to 999 how can i find is there any formula i know the formula to get numbere thatis biger no. - smaller no+1

You can find the required number of even numbers from 100 to 999 by making use of the concept of probability.

 

The even numbers will be 100, 102, ... ... 998.

This is an AP with first term 100 and common difference 2.

 

Let the number of terms be n.

Then a_n = 998

a + (n - 1)d = 998

100 + (n - 1)2 = 998

2 (n - 1) = 898

n - 1 = 449

n = 450

Hence, there are 450 even numbers from 100 to 999.