Question

bài3,tính các tích sau bằng cách nhanh nhất

a,2x9x5

b,7x4x25

c,125x8x6

d,8x12x125

e,16x2x4x5

f,25x3x7x4

g,9x4x25x8x125

h,8x25x2x4x125

i,27x38+27x62

k,19x25+19x45+19x30

l,36x(143+57)+64x(143+57)

m,53x11

n,28x101

Answer 1

a, 2 . 9 . 5 = ( 2.5 ) . 9 = 10 . 9 = 90

b, 7 . 4 . 25 = ( 4 . 25 ) . 7  = 100 . 7 = 700

c, 125 . 8 . 6 = ( 125 . 8 ) . 6 = 1000 . 6 = 6000

d, 8 . 12 . 125 = 12 . ( 8 . 125 ) = 12 . 1000 = 12000

e, 16 . 2 . 4 . 5 = ( 16 . 4 ) . ( 2 . 5 ) = 64 . 10 = 640

f, 25 . 3 . 7 . 4 = ( 25 . 4 ) . ( 3 . 7 ) = 100 . 21 = 2100

g, 9 . 4 . 25 . 8 . 125 = ( 25 . 4 ) . ( 125 . 8 ) . 9 = 100 . 1000 . 9 = 900000

h, 8 . 25 . 2 . 4 . 125 = ( 25 . 4 ) . ( 8 . 125 ) . 2 = 100 . 1000 . 2 = 200000

i, 27 . 38 +27 . 62 = 27 . ( 38 + 62 ) = 27 . 100 = 2700

k, 19 . 25 + 19 . 45 + 19 . 30 = 19 . ( 25 + 45 + 30 ) = 19 . 100 = 1900

l, 36 . ( 143 + 57 ) + 64 . ( 143 + 57 ) = 36 . 200 + 64 . 200 = (36 + 64 ) . 200 = 100 . 200 = 20000

m, 53 . 11 = 53 . ( 10 + 1 ) = 53 . 10 + 53 . 1 = 530 + 53 = 583

n, 28 . 101 = 28 . ( 100 +1 ) = 28 . 100 + 28 . 1 = 2800 + 28 = 2828