a) \(53.39+47.39-53.21-47.21\)
\(=39\left(53+47\right)-21\left(53+47\right)\)
\(=39.100-21.100\)
\(=3900-2100=1800\)
b) \(\left(252+2.28-5.28\right):28\)
\(=\left(9.28+2.28-5.28\right):28\)
\(=28\left(9+2-5\right):28\)
\(=28.6:28\)
\(=6\)
tinh nhanh:53.39+47.39-53.21-47.21
Tính nhanh:
a)53.39+47.39-53.21-47.21
b)2.53.12+4.6.87-3.8.40
c)3.7.77-7.60+49.25-15.42
Tính : B=53.39+47.39-53.21-47.21
tính nhanh
53.39+47.39+53.21+47.21
2.53.12+4.6.87 -3.8.40
5.7.77-7.60+49.25-12.42
Tính :a,1+(-3)+5+(-7)+...+72 b, 53.39+47.39-53.21-47.21
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
