Question

Bài 2. Tính nhanh:
 
a) 27.19 + 73.20
 
b) 42.50 - 38.50 - 25.4
 
e) 254.58 + 21.508
 
c) 12.53 + 53.172 - 53.84
 
d) 2.31.12 + 4.6.42 + 8.27.3
 
f) (9 - 8 - 7 -... - 2 -1).(500.9 - 250.18)

 

Answer 1

Mn giúp e vs ạ, em chuẩn bị phải nộp bài rùi T - T

Answer 2

\(a,=27\cdot20+73\cdot20-27=20\left(27+73\right)-27\\ =20\cdot100-27=2000-27=1973\\ b,=42\cdot50-38\cdot50-50\cdot2=50\left(42-38-2\right)=50\cdot2=100\\ e,=254\left(58+21\cdot2\right)=254\cdot100=25400\\ c,=53\left(12+172-84\right)=53\cdot100=5300\\ d,=24\left(31+42+27\right)=24\cdot100=2400\\ f,=\left(9-8-...-1\right)\left(500\cdot9-500\cdot9\right)=\left(9-8-...-1\right)\cdot0=0\)

Answer 3

a. 27*(20-1)+73*20=27*20-27+73*20=20*(27+73)-27=20*100-27=2000-27=1973

b. =42*50-38*50-50*2=50*(42-38-2)=50*2=100

C. =53*(12+172-84)=53*100=5300

D.=31*24+24*42+24*27=24*(31+42+27)=24*100=2400

E.=508*29+21*508=508*(29+21)=508*50=25400