Question

Bài 1: Tính tổng:

     a)   S = 1+2+3+….+2021                                      b) P = 1+3+5+……+2021

     c) Q = 2+4+6+.......+ 2020                                     d) M = 1+4+7+.....+298

Answer 1

a) \(S=1+2+3+...+2021\)

\(=\left(2021+1\right).2021:2\)

\(=2043231\)

b) \(P=1+3+5+...+2021\)

\(=\left(2021+1\right).[\left(2021-1\right):2+1]:2\)

\(=2022.1011:2\)

\(=1022121\)