Question

find the sum write the formula also.
1+2+3+...+20
2+4+6+...+20
1+3+5+...+19​

Answer 1

Answer:

$1 + 2 + 3 + ... + 20 = 210 \\ 2 + 4 + 6 + ... + 20 = 110 \\ 1 + 3 + 5 + ... + 19 = 100$