Question

Tính bằng cách thuận tiện nhất:

a)2,5x16,27x4

b)0,25x1,25x4x8

c)6,7x9,55+9,45x16,7+16,7

d)\(\frac{3}{4}X\frac{4}{5}+\frac{5}{6}X\frac{6}{7}X\frac{7}{8}\)

\(X\)là dấu nhân nha !

Answer 1

a)2,5*16,27*4=(2,5*4)*16,27=10*16,27=162,7.

b)0,25*1,25*4*8=(0,25*4)*(1,25*8)=1*10=10.

d)3/4*4/5+5/6*6/7*7/8=3*4/4*5+5*6*7/6*7*8=3/5+5/8=49/40.

Answer 2

a) 2,5 x 16,27 x 4

= (2,5 x 4) x 16,27

= 10 x 16,27

= 162,7

b) 0,25 x 1,25 x 4 x 8

= (0,25 x 4) x (1,25 x 8)

= 1 x 10

= 10

c) 6,7 x 9,55 + 9,45 x 16,7 + 16,7

= 6,7 x 9,55 + (9,45 + 1) x 16,7

= 6,7 x 9,55 + 10,45 x 16,7

= 63,985 + 174,515

= 238,5

d) 3/4 x 4/5 + 5/6 x 6/7 x 7/8

= 3/4 x 4/5 + 5/6 x 3/4

= 3/4 x (4/5 + 5/6)

= 3/4 x 49/30

= 49/40