Question

[Nguyễn Thạc Duy Hưng]

tinh nhanh

30+31+31+32+33+34+35+36+37+38+39

Answer 1

[Lê Thị Kiều Ngân]

(31+39)+(32+38)+(33+37)+(34+36)+(30+31+35)=70+70+70+70+96=376
 

Answer 2

[Miyoko]

30+31+32+33+34+35+36+37+38+39

=30+(31+39)+(32+38)+(33+37)+(34+36)+35

=30+70+70+70+70+35

=30+280+35

=310+35

=345