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

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

thanks

a: =20x71=1420

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

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

a.=(4345+3845):126=8190:126=65b.=(24563−12215):126=12348:126=98

316x( 96+3+1)

=316x 100

=31600

164x(50x2)

=164x 100

=16400

a. 316 x 96 + 316 x 3 + 316

= 316 x ( 96 + 3 + 1)

= 316 x 100 

= 31600

b. 164 x 50 x 2

= 164 x 100

= 16400

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

=36,5x10

=365

36,5 : 0,5 + 36,5 \(\times\) 9 -36,5

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

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

\(=36,5\times10\)

\(=365\)

lm theo cách này nhé :\

36,5 : 0,5 + 36,5  9 -36,5

36,5x2+36,5x9-36,5

=36,5x10

=365

oki :)

a. 125 x 25 x 8

=(125x8) x25

=    1000 x25

= 25000

a. 125 x 25 x 8

= ( 125 x 8 ) x 25 

= 1000 x 25

= 25000

=1000x25=25000

a) 4 x 78 x 5

= (4 x 5) x 78

= 20 x 78

= 1560

b) 2 x 99 x 5

= (2 x 5) x 99

= 10 x 99

= 990

\(7,\)

\(a,=\left(4\times5\right)\times78=20\times78=1560\)

\(b,=\left(2\times5\right)\times99=10\times99=990\)

a. 4 x 78 x 5 = 4 x 5 x 78 = 20 x 78 = 1560

b. 2 x 99 x 5 = 2 x 5 x 99 = 10 x 99 = 990

Bài 8: Tính bằng cách thuận tiện nhất:
a, 6 x 31 x 5 =(6x5)x31
                    =30x31
                    =930

b, 8 x 63 x 5 =(8x5)x63
                     =40x63
                     =2520

a.

6 x 31 x 5

= (6 x 5) x 31

= 30 x 31

= 930

b.

8 x 63 x 5

= (8 x 5) x 63

= 40 x 63

= 2520

a, 6 x 31 x 5= (6 x 5) x 31

                    =30 x 31

                    = 930

b, 8 x 63 x 5= ( 8 x 5) x 63

                    = 40 x 63

                    = 2520