Question

Bài 3: Tính nhanh

34, 65 + 21,78 + 65,35 + 78, 22          4,5 x 5,5 + 4,7 x 4,5                     7,5 x 2,5 x 4          

Answer 1

34,65 + 21,78 + 65,35 + 78,22

= (34,65 + 65,35) + (21,78 + 78,,22)

= 100 + 100

= 200

4,5 x 5,5 + 4,7 x 4,5

= 4,5 x (5,5 + 4,5)

= 4,5 x 10

= 45

7,5 x 2,5 x 4

= 7,5 x 10

= 75

 

Answer 2

\(34,65+21,78+65,35+78,22=\) 

\(=\left(34,65+65,35\right)+\left(21,78+78,22\right)\)

\(=100+100\)

\(=200\)

\(4,5\times5,5+4,7\times4,5=\)

\(=4,5\times\left(5,5+4,7\right)\)

\(=4,5\times10,2\)

\(=45,9\)

 \(7,5\times2,5\times4=\)

\(=7,5\times\left(2,5\times4\right)\)

\(=7,5\times10\)

\(=75\)