Question

Tính bằng cách thuận tiện.

a) 275 + (725 + 486)                       b) (3,29 + 4,63) + 5,37

c) 63,4 + 597 + 36,6                       d) \(\dfrac{4}{9}+\dfrac{7}{12}+\dfrac{5}{12}+\dfrac{5}{9}\)

Answer 1

a) 275 + (725 + 486) = (275 + 725) + 486 = 1 000 + 486 = 1 486

b) (3,29 + 4,63) + 5,37 = 3,29 + (4,63 + 5,37) = 3,29 + 10 = 13,29

c) 63,4 + 597 + 36,6 = (63,4 + 36,6) + 597 = 100 + 597 = 697

d) $\frac{4}{9} + \frac{7}{{12}} + \frac{5}{{12}} + \frac{5}{9} = \left( {\frac{4}{9} + \frac{5}{9}} \right) + \left( {\frac{7}{{12}} + \frac{5}{{12}}} \right) = 1 + 1 = 2$