Question

Tính bằng cách thuận tiện:

( 36 x 27 ) : 3

( 125 x 15 ) : 5

( 15 x 12 ) : 9

450 : ( 3 x 5)

( 45 x 63 ) : 9

Answer 1

(36 × 27) : 3 = 36 × (27 : 3)

= 36 × 9

= 324

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(125 × 15) : 5

= 125 × (15 : 5)

= 125 × 3

= 375

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(15 × 12) : 9

= (5 × 3 × 12) : 9

= 5 × (36 : 9)

= 5 × 4

= 20

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450 : (3 × 5)

= 450 : 15

= 30

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(45 × 63) : 9

= 45 × (63 : 9)

= 45 × 7

= 40 × 7 + 5 × 7

= 280 + 35

= 315

Answer 2

a: \(\dfrac{\left(36\cdot27\right)}{3}=36\cdot\dfrac{27}{3}=36\cdot9=324\)

b: \(\dfrac{\left(125\cdot15\right)}{5}=125\cdot\dfrac{15}{5}=125\cdot3=375\)

c: \(\dfrac{\left(15\cdot12\right)}{9}=\dfrac{3\cdot3\cdot4\cdot5}{9}=4\cdot5=20\)

d: \(\dfrac{450}{3\cdot5}=\dfrac{450}{15}=30\)

e: \(\dfrac{45\cdot63}{9}=\dfrac{45}{9}\cdot63=63\cdot5=315\)

Answer 3