Question

Tính hợp lí (nếu có thể):
a) 278 + 809 + 622 - 209
b) 64.57+64.43−2300
c) 24.5−[131−(13−4)2]

Answer 1

a) \(=\left(278+622\right)+\left(809-209\right)=900+600=1500\)

b) \(=64.57+64.43-2300=64\left(57+43\right)-2300=54.100-2300=5400-2300=3100\)

 

Answer 2

a) 278+809+622-209
  = (278+622)+(809-209)
  =       900    +    600
  =              1500
b) 64.57+64.43-2300
  = 64(57+43)-2300
  = 64.100-2300
  = 6400-2300=4100
c) 24.5-[131-(13-4)2]
  = 24.5-(131-9.2)
  = 120-113= 7