Question

find the sum of all even integer 101 and 999

Answer 1

all even integer no is 102

Answer 2

“Sum of first 'n' even integers = n(n+1)”

“Sum of all even integers between 101 and 999”

= (Sum of all even integers between 1 and 9999) – (Sum of all even integers between 1 and 101)

“= 9999(9999+1) - 101(101+1)”

“= 9999(10000) - 101(102)”

“=99990000 – 10302 = 99979698”