Question

Bài 1 : tính nhanh

1+4+7+10+13+16+19

34+77-66+13

Answer 1

1 + 4 + 7 + 10 + 13 + 16 + 19 = 70

34 + 77 - 66 + 13 = 58

Answer 2

\(1+4+7+10+13+16+19=\left(1+19\right)+\left(4+16\right)+\left(7+13\right)+10=20+20+20+10=70\)

\(34+77-66+13=58\)

Answer 3

58