Question

tính nhanh :

a, -79 - 79 . 99

b, -123 . 47 + 47 . 23

c, 19 - 42 . ( - 19 ) + 38 . 5

Answer 1

a) -79 - 79.99 = -79(1 + 99) = -79.100 = -7900

 

Answer 2

b) -123.47 + 47.23 = -47(123 - 23) = -47.100 = -4700

 

Answer 3

c) 19 - 42.(-19) + 38.5 = 19 + 42.19 + 38.5 = 19(1 + 42 + 10) = 19.53 = 20.53 - 53 = 1060 - 53 = 1007