Question

find the (i) sum of those integers between 1 and 500 which are multiples of 2 as well as of 5. (ii) sum of those integers from 1 to 500 which are multiples of 2 as well as of 5 . (iii) sum of those integers from 1 to 500 which are multiples of 2 or 5.

Answer 1

AP=10,20,30...,500.

an=500,a=10,d=10

an=a+(n-1)d

500=10+(n-1)*10

(500-10)/10 +1=n

50=n

Sn=n/2(a+an)

=50/2(10+500)

=12750

Answer 2

Answer:

(i) 12250

(ii) 12750

(iii) 75250