Question

Tính nhanh.

a,15.37.4+120.21+21.5.12

b,15(27+18+6) + 15(23+12)

c,10(81 + 19) +100 + 50( 91+ 9)

d,42(15 + 96) + 6(25 +4).7

Answer 1

a) 15.37.4 + 120.21 + 21.5.12

= 60 . 37 + 2.60.21 + 60 . 21

= 60 (37 + 42 + 21)

= 60 x 100 = 6000

b) 15.(27 + 18 + 6) + 15 . (23 + 12)

= 15 . (27 + 18 + 6 + 23 + 12)

= 15 x 86

=1290

c) 10 x (81 + 19) + 100 + 50 x (91 + 9)

= 10 x 100 + 100 + 50 x 100

= 100 x (10 + 1 + 50)

= 100 x 61 = 6100

d) 42 x (15 + 96) + 6 x (25 + 4) x 7

= 42 x (15 + 96) + 42 x (25 + 4)

= 42 x (15 + 96 + 29)

= 42 x 140 =5880