Question

1+2-3-4+5+6-7-8+9+...+402-403-404+405+406

Answer 1

\(\text{1+2-3-4+5+6-7-8+9+...+402-403-404+405+406}\)

\(=406+\left(405-404-403+402\right)+\left(401-400-399+398\right)+...\left(5-4-3+2\right)+1\)

\(=406+0+0+...+0+1\)

\(=407\)

Answer 2

1 +2 - 3 - 4 + 5 + 6 - 7 - 8 + 9 + ....... + 402 - 403 - 404 + 405 + 406

= 406 + ( 405 - 404 - 403 + 402 ) + ( 401 - 400 - 399 + 398 ) + ......... + ( 5 - 4 - 3 + 2 ) + 1

= 406 + 0 + 0 + ....... + 0 + 1

 = 407