Question

1-2+3-4+5-6+...+19-20.
sooo.
what will be the answer.
solve the sum by giving method.

Answer 1

1-2+3-4+5-6+7-8+9-10+11-12+13-14+15-16+ 17-18+19-20
=>by adding all the digits we get
=> -1-1-1-1-1-1-1-1-1-1=-10 answer
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