53.39+47.39-53.21-47.21
53.39+47.39-53.21-47.42
53.39+47.39-53.21-47.21
53.39-47.39-53.21-47.21
Tính : B=53.39+47.39-53.21-47.21
tinh nhanh:53.39+47.39-53.21-47.21
53.39-47.39-53.21+2.53.12+4.6.87-3.8.40
53.39 + 47.39 - 53. 21 - 47. 21 + 2.53.12 + 4.6.87 -3.8.40
Tính nhanh :
a. 53.39 + 47.39 - 53.21 - 47.21
b. ( 252 + 2. 28 - 5.28 ) : 28