Question

Find the sum of those integer from 1 to 500 which are multiple of 2 as well as 5

Answer 1

The first number between from 1 and 500 which is a multiple of both 2 and 5 is '10'

The last number is '500'

So, the numbers are 10, 20, 30,........, 480, 490, 500
This is an A.P(Arithmetic Progression) with common difference (d) = 10
A1 = 10
An = 500
An = A1 + (n-1)*d
500 = 10 + (n-1)*10
490 = (n-1)*10
49 = n-1
n = 50
The sum of an A.P is:
Sum = n/2 * (A1 + An)
     = 50/2 * ( 10 + 500)
     = 12750
Hence sum of numbers from 1 to 500 which is a multiple of both 2 and 5 is 12750.
Hope it helps. 

Answer 2

Answer:

12750 is the answer......