b) 168 + 2080 + 32= (168 + 32) + 2080

= 200 + 2080 = 2280

87 + 94 + 13 + 6= ( 87 + 13) + (94 +6)

= 100 + 100

121 + 85 + 115 +469= (121 + 469) + ( 85 + 115)

= 590 + 200 = 790.

168 + 2080+ 32

= ( 168 + 32 ) + 2080

= 200 + 2080

= 2280.

87 + 94 + 13 + 6

= ( 87 + 13 ) + ( 94 + 6 )

= 100 + 100

= 200.

121 + 85 + 115 + 469

= ( 121 + 469 ) + ( 85 + 115 )

= 590 + 200

= 790.

a, 168+2080+32

=(168+32)+2080

=200+2080

=2280

b,87+94+13+6

=(87+13)+(94+6)

=100+100

=200

c,121+85+115+469

=(121+469)+(85+115)

=590+200

=790

168+2080+32=(168+32)+2080=200+2080=2280

87+94+13+6=(87+13)+(94+6)=100+100=200

121+85+115+469=(121+469)+(115+85)=590+200=790

k mk nha bn

( 168 x 168 - 168 x 58 ) : 110

= [ 168 x ( 168 - 58 ) ] : 110

= 168 x 110 : 110

= 168

168 x 110 : 110 = 168

( 168 x 168 - 168 x 58 ) : 110 = [ 168 x ( 168 - 58 ) ] : 110

                                           = [ 168 x 110 ] : 110

                                           = 18480 : 110

                                           = 168

25 × 32 × 2 × 4

= (25 x 4) x (32 x 2)

= 100 x 64

= 6400

=6400

\(\left(25\times32\right)\div4\\ =25\times32\div4\\ =25\times\left(32\div4\right)\\ =25\times8\\ =200\)

`(25 \times 32) \div 4`

`= (25 \times 4 \times 8) \div 4`

`= (100 \times 8) \div 4`

`= 800 \div 4`

`= 200`

Có số số hạng là:

\(\left(39-30\right)\div1+1=10\) (số hạng)

Có số cặp là:

\(10\div2=5\)(cặp)

30 + 31 + 32 + ... + 38 + 39

= (31 + 39) + (32 + 38) + (33 + 37) + (34 + 36) + (30 + 35)

= 70 + 70 + 70 + 70 + 65

= 70 x 4 + 65

= 280 + 65

= 345

1/4

\(=\dfrac{8}{15}\left(\dfrac{25}{32}-\dfrac{10}{32}\right)=\dfrac{8}{15}\cdot\dfrac{15}{32}=\dfrac{1}{4}\)

( 25/32 - 10/32) x 8/15

 = 15/32 x 8/15

= 1/4

   32 - 16 + 28 - 24

= ( 32 + 28 ) - ( 16 + 24 )

=       60       -     40

=                20

32-16+28-24

=(32+28)-(16+24)

=60-40

=20

chúc các bn cuối tuần vui vẻ !

\(32-16+28-24\)

\(=\left(32+28\right)-\left(16+24\right)\)

\(=60-40\)

\(=20\)

     (32+58)×8+8×9+8

= 8×(32+58+9+1)

= 8 × 100

= 800

(32 + 58) x 8 + 8 x9 + 8

= 8 x ( 32 + 58 + 9 +1 )

= 8 x 100 = 800.

Chúc Em Học Tốt