Tính bằng cách thuận tiện nhất:

a) 1,25 x 3,6 + 2,5 x 7,2 x 5 -1,25 x 8

= 1,25 x 4 x 0,9 + 2,5 x 2 x 3,6 x 5 - 1,25 x 4 x 2

= 5 x 0,9 + 5 x 18 - 5 x 2 

= 4,5 + 90 - 10

= 84,5

b) 4,16 x 4/5 -80% x 0,16 + 0,96: 1,2

= 4,16 x 0,8 - 0,8 x 0,16 + 0,8

= 0,8 x (4,16 - 0,16 + 1)

= 0,8 x 5 = 4

\(2,53\times75-16,1\times3,7+2,53\times25-16,1\times6,3\)
\(=2,53\times\left(75+25\right)-16,1\times\left(3,7+6,3\right)\)
\(=2,53\times100-16,1\times10\)
\(=253-161\)
\(=92\)

bạn Komuro Tairoku chú ý: chỉ có 1 dấu phẩy

\(a,\\7,82+1,47+0,18\\=(7,82+0,18)+1,47\\=8+1,47\\=9,47\\---\\b,\\2,71+5,9+1,29+33,1\\=(2,71+1,29)+(5,9+33,1)\\=4+39\\=43\\\text{#}Toru\)

a: 7,82+1,47+0,18

=7,82+0,18+1,47

=8+1,47

=9,47

b: 2,71+5,9+1,29+33,1

=2,71+1,29+5,9+33,1

=4+39

=43

a: =20x71=1420

\(a.=\left(4345+3845\right):126\\ =8190:126=65\\ b.=\left(24563-12215\right):126\\ =12348:126=98\)

\(a,4345:126+3845:126=\left(4345+3845\right):126=8190:126=65\\ b,24563:126-12215:126=\left(24563-12215\right):126=12348:126=98\)

316x( 96+3+1)

=316x 100

=31600

164x(50x2)

=164x 100

=16400

96+3 = ??

a: 5,67x2,5x0,4=5,67

1,4x3,6+1,4x6,4=1,4x10=14

b: 0,25x0,68x40=10x0,68=6,8

25,8x1,02-25,8x1,01=25,08x0,01=0,2508

a: Sửa đề: 0,73x65+0,75x8+35x0,73+0,5x8

Ta có: 0,73x65+0,75x8+35x0,73+0,5x8

\(=0,73\times\left(65+35\right)+8\times\left(0,75+0,5\right)\)

=0,73x100+8x1,25

=73+10

=83

b: \(12,3\times4,7+5,3\times12,3-1,4\times7,5+7,5\times5,4\)

\(=12,3\times\left(4,7+5,3\right)+7,5\times\left(5,4-1,4\right)\)

\(=12,3\times10+7,5\times4\)

=123+30

=153

c: \(13,7\times18+82\times10,5+3,2\times82\)

\(=13,7\times18+82\times\left(10,5+3,2\right)\)

\(=13,7\times18+82\times13,7\)

\(=13,7\times\left(18+82\right)=13,7\times100=1370\)

a: =36,5x2+36,5x9-36,5

=36,5x10

=365

36,5 : 0,5 + 36,5 \(\times\) 9 -36,5

\(=36,5.2+36,5\times9-36,5\)

\(=36,5\times\left(2+9-1\right)\)

\(=36,5\times10\)

\(=365\)