Question

[Nguyễn Hữu Thế]

Tính bằng cách thuận tiện nhất

a)  1987+1992+1997+2002+2007

b)  4,25+4,32+4,39+4,46+4,53

c)  \(\frac{3}{5}+\frac{3}{4}+\frac{2}{5}+\frac{5}{8}+\frac{1}{2}\)

Answer 1

[Trần Thu Hằng]

c) \(\frac{3}{5}+\frac{3}{4}+\frac{2}{5}+\frac{5}{8}+\frac{1}{2}\)

= \(\frac{3}{5}+\frac{2}{5}+\left(\frac{6}{8}+\frac{5}{8}+\frac{4}{8}\right)\)

= 1 + \(\frac{15}{8}\)

= 2\(\frac{7}{8}\)

Answer 2

[Vũ Thảo Nguyên]

3/5+3/4+2/5+5/8+1/2

=(3/5+2/5)+(3/4+1/2)+5/8

=1+5/4+5/8

=1+15/8=23/8