Question

Find the sum of all two-digit numbers that give a remainder of 3 when they are divided by 7.

Options

• 686

• 676

• 666

• 656

Answer 1

676

First 2 digit number which leaves 3 when divided by 7 is 10 Last 2 digit number which leaves 3 when divided by 7 is = 94

a_n = a + (n - 1) d

94 = 10 + (n - 1) 7

`84/7 = "n" - 1`

n = 13

`"S"_13 = 13/2[10+94] = 13/2xx104=676`