Question

find the sum and write the steps
1+2+3+...100
1+3+5+...99
2+4+6+...100
3+7+11...199​

Answer 1

Answer:

$1 + 2 + 3 + ...100 = 2550 \\ 1 + 3 + 5 + ..99 = 1250 \\ 2 + 4 + 6..100 = 1300$