Question

Determine the sum for the positive two-digit integers that are not divisible by 5.

A. 3960
B. 1640
C. 2830
D. 4550

Answer 1

Determine the sum for the positive two-digit integers that are not divisible by 5.

11, 12, 13, 14, 16, 17, 18, 19, 21 ... 99

lets do this

S(90) = (90/2)(11 + 99)
S(90) = 4950

but were not done yet

10, 15, 20, 25, 30, 35, ... 95

S(9) = (9/2)(10 + 90) + (9/2)(15 + 95)
S(9) = (18/2)(100 + 110)
S(9) = 1890

now we just subtract 1890 from 4950

ANS : 3060

Answer 2

3060 is not one of the choices

Answer 3

I think its A

Answer 4

it means :
(10+11+12+13+...+99) - (10+15+20+25+...+95)
= ...

Answer 5

Okay