Question

How many integers between 199 and 599 are multiple of 3

Answer 1

A.P. series would be: 201, 204, 207 .... 597
Here, a = 201, d = 3, l = 597

Now, l = a + (n - 1) d
597 = 201 + (n - 1)3
597 - 201 = 3n - 3
396 + 3 = 3n
n = 399/3
n = 133

In short, Your Answer would be 133

Hope this helps!

Answer 2

Fabulous question!
1st determine the entire sum of integers from 199 to 599
599 - 199 = 400

3x = 400
x = 133 integer approx