A: 

*24 x 5 + 24 x 3 + 24 x 2= 24 × (5+3+2)= 24×10=240

* 24 x 5 + 24 x 4 + 24=24 x 5 + 24 x 4 + 24×1=24×(5+4+1)=24×10=240

* 217 x 45 + 50 x 217 + 207 x 5= 217×(45+50) +207 ×5=217×95+207+5 =20615 +1035=21650

* 456 x 36 + 456 x 61 + 4 x 456 + 456

= 456 x 36 + 456 x 61 + 4 x 456 + 456 ×1

= 456×(36+61+4+1)

=456×102=46512

* (16 x 6+ 16 x3 + 16) - (12 x 65 + 12 x 3 + 2 x12)

=(16 x 6+ 16 x3 + 16×1) - (12 x 65 + 12 x 3 + 2 x12)

=[16×(6+3+1)]-[12×(65+3+2)]

=(16×10)-(12×70)

=160×840=134 400

* 213 x 37 + 213 x 39 + 23 x 213 + 213 

=213 x 37 + 213 x 39 + 23 x 213 + 213 ×1

=213×(37+39+23+1)

=213×100=21300

* 9 + 9 x 3 + 18 : 2 x 6= 9×1 +9×3+9×2 : 2 x 6=9×(1+3+2 : 2 x 6)=9×10=90

* 2007 x 16 - 2007 x 14 - 2007 x 2 + 2007

=2007 x 16 - 2007 x 14 - 2007 x 2 + 2007×1

=2007×(16-14-2+1)

=2007×1=2007

* 3 x 9 + 18 x 2 + 2 x 9 + 9=3 x 9 + 9x 2×2 + 2 x 9 + 9×1=9×(3+2×2+2+1)=9×10=90

* ( 145 x 99 + 145) - ( 143 x 101 - 143 )

=( 145 x 99 + 145×1) - ( 143 x 101 - 143 ×1)

=[145×(99+1)]-[143×(101-1)]

=145×100-143×100

=(145-143)×100

=2×100=200

* 2006 x ( 43 x 10 - 2 x 43 x 5) + 100=2006×0+100=100

* 64 x 4 + 18 x 4 + 9 x 8= 64 x 4 + 18 x 4 + 9 x 2×4=(64+18+9×2)×4=100×4=400

* 44 x 5 + 18 x 10 + 20 x 5 =44 x 5 + 18 x 5×2+ 20 x 5 =(44+18×2+20)×5=100×5=500

* 3 x 4 + 4 x 6 + 9 x 2 + 18=3 x 4 + 4 x 3×2 + 3×3 x 2 + 3×6=3×(4+4×2+3×2+6)=3×24=72

* 2 x 5 + 5 x 7 + 9 x 3=5×(2+7)+9×3=5×9+9×3=9×(5+3)=9×8=72

* 15 : 5 + 27 : 5 + 8 : 5 =$\frac{(15+27+8)}{5}$ =$\frac{50}{5}$ =10

* 99 : 5 - 26 : 5 - 14 : 5=$\frac{(99-26-14)}{5}$ =$\frac{59}{5}$ 

B:

* ( 18 - 9 x 2) x ( 2 + 4 + 6 + 8 + 10 )=(18-18)x ( 2 + 4 + 6 + 8 + 10 )=0x ( 2 + 4 + 6 + 8 + 10 )=0

⇒ Tương tự như trên mấy bài tập phía dưới mình làm nhanh nhé 

* ( 7 x 8 - 56 ) :( 2 + 4 + 6 + 8 + 10 )

=0: ( 2 + 4 + 6 + 8 + 10 )=0

* ( 7 x 8 - 56 )x ( 42 - 6 x 7 )=0×0=0

*( 12 x 6 - 12 x 4 - 12 x 2 ) x ( 42 - 6 x 7 )=( 12 x 6 - 12 x 4 - 12 x 2 ) x0=0

*(a x 7 + a x 8 - a x 15) : ( 1 + 2 + 3 + ........ + 10)

=[a×(7+8-15)]: ( 1 + 2 + 3 + ........ + 10)

=0: ( 1 + 2 + 3 + ........ + 10)=0

*58 - 58 x( 6 + 54 - 60)=58 - 58 x0=58-0=58

* 32 + 63 × a × ( a × 1 - a : 1) + 32 x 8 + 32=32 + 63 × a × 0+ 32 x 8 + 32=32 +0+ 32=64

* ( 1 + 2 + 3 + 4 + .... + 9 ) x ( 21 x 5 - 21 - 4 x21)

=( 1 + 2 + 3 + 4 + .... + 9 ) x ( 21 x 5 - 21 ×1- 4 x21)

=( 1 + 2 + 3 + 4 + .... + 9 ) x[21×(5-1-4)]

=( 1 + 2 + 3 + 4 + .... + 9 )×0=0

* ( 9 x 7 + 8 x 9 - 15 x 9 ) : ( 1 + 3 + 5 + 7 + ........+ 17 + 19 )

=[9×(9+7+8-15)]: ( 1 + 3 + 5 + 7 + ........+ 17 + 19 )

=0: ( 1 + 3 + 5 + 7 + ........+ 17 + 19 )=0

* ( 2 + 4 + 6 + 8 + ... + 20 ) x ( 56 x 3 - 72 : 9 x 21)

= ( 2 + 4 + 6 + 8 + ... + 20 ) x(8×7×3-8×9:9×21)

=( 2 + 4 + 6 + 8 + ... + 20 ) x[8×(7×3-9:9×21)]

=( 2 + 4 + 6 + 8 + ... + 20 )×(8×0)

=( 2 + 4 + 6 + 8 + ... + 20 )×0=0

Học Tốt Nhé

Dạng1

$*24×5+24×3+24×2\\=24×(5+3+2)\\=24×10=240$

$*24×5+24×4+24\\=24×(5+4+1)\\=24×10=240$

$*217×45+50×217+217×5\\=217×(45+50+5)\\=217×100=21700$

$*456×36+456×61+4×456+456\\=456×(36+61+4+1)\\=456×100=45600$

$*(16×6+16×3+16)-(12×5+12×3+2×12)\\=16×(6+3+1)-(12×(5+3+2)\\=16×10-12×10\\=10×(16-12)\\=10×4=40$

$*(16×6+16×3+16)-12×5-12×3-2×12\\=16×(6+3+1)-12×(5+3+2)\\=16×10-12×10\\=10×(16-12)\\=10×4=40$

$*213×37+213×39+23×213+213\\=213×(37+39+23+1)\\=213×100=21300$

$*9+9×3+18:2×6\\=9×(1+3+6)\\=9×10=90$

$*2007×16-2007×14-2007×2+2007\\=2007×(16-14-2+1)\\=2007×1=2007$

$*3×9+18×2+2×9+9\\=9×(3+4+2+1)\\=9×10=90$

$*(145×99+145)-(143×101-143)\\=145×(99+1)-143×(101-1)\\=145×100-143×100\\=100×(145-143)\\=100×2=200$

$*2006×(43×10-2×43×5)+100\\=2006×(43×10-43×10)+100\\=2006×0+100=100$

$*64×4+18×4+9×8\\=4×(64+18+18)\\=4×100=400$

$*44×5+18×10+20×5\\=5×(44+36+20)\\=5×100=500$

$*3×4+4×6+9×2+18\\=4×(3+6)+9×(2+2)\\=4×(3+6+9)\\=4×18=72$

$*2×5+5×7+9×3\\=5×(2+7)+9×3\\=9×(5+3)\\=9×8=72$

$*15:5+27:5+8:5\\=(15+27+8):5\\=40:5=8$

$*99:5-26:5-14:5\\=(99-26-14):5\\=59:5$

Dạng 2

$*(18-9×2)×(2+4+6+8+10)\\=(18-18)×(2+4+6+8+10)\\=0×(2+4+6+8+10)=0$

$*(7×8-56):(.........)\\=(56-56):(.......)\\=0:(.........)=0$

$*(.....)×(42-6×7)\\=(.....)×(42-42)\\=(.....)×0=0$

$*(12×6-12×4-12×2)×(.....)\\=(12×(6-4-2)×(.....)\\=(12×0)×(.....)\\=0×(.....)=0$

$*58-58×(6+54-60)\\=58-58×0=58$

$*32+63×a×(a×1-a:1)+32×8+32\\=32×(1+8+1)+63×a×(a-a)\\=32×10+63×a×0\\=320$

$*(1+2+3+4+...+9)×(21×5-21-4×21)\\=(1+2+3+4+...+9)×(21×(5-1-4))\\=(1+2+3+4+...+9)×(21×0)\\=(1+2+3+4+...+9)×0=0$