1. Đặt tính rồi tính a. 371 x 412 b. 312 x27 c4560 : 140 d. 2798 : 125 2. Tính bằng cách thuận tiện a. 37x2x8x5 b . 42x4x3x25 c. 125x6x7x8 d. 132x63+132x37 e. 127x42+53x42+42x30 g. 141x58+129x37+141x42 + 129x63 h. 132x145-132x45 i.185:5 k. 150 :25 m. 32x25

1) 

371.412=152852

312.27=8424

4560:140=228/7

2798:125=22,384

2)

a) 37.2.8.5=(37.8).(2.5)=296.10=2960

b) 42.4.3.25=(42.3).(4.25)=126.100=12600

c) 125.6.7.8=(6.7).(125.8)=42.1000=42000

d) 132.63+132.37=132.(63+37)=132.100=13200

e) 127.42+53.42+42.30=42.(127+53+30)=42.200=8400

g) 141.58+129.37+141.42+129.63=[141.(58+42)]+[129.(63+37)]

=[141.100]+[129.100]=14100+12900=27000

h) 132.145-132.45=132.(145-45)=132.100=13200

 i) 185:5=37

k) 150:25=6

m) 32.25=800

Đáp án:

`1) `

`371.412=152852`

`312.27=8424`

`4560:140=228/7`

`2798:125=22,384`

`2)`

`a) 37.2.8.5=(37.8).(2.5)=296.10=2960`

`b) 42.4.3.25=(42.3).(4.25)=126.100=12600`

`c) 125.6.7.8=(6.7).(125.8)=42.1000=42000`

`d) 132.63+132.37=132.(63+37)=132.100=13200`

`e) 127.42+53.42+42.30=42.(127+53+30)=42.200=8400`

`g) 141.58+129.37+141.42+129.63=[141.(58+42)]+[129.(63+37)]`

`=[141×100]+[129×100]=14100+12900=27000`

`h) 132×145-132×45=132×(145-45)=132×100=13200`

 `i) 185÷5=37`

`k) 150÷25=6`

`m) 32×25=800`