Question

 Tính bằng cách thuận tiện

1/10 + 12/20 + 3/30 + 4/40 + 5/50 + 6/60 + 7/70 + 8/80 + 9/90 

 

Answer 1

9/10 nha

Answer 2

=\(\frac{1}{10}\cdot9\)

=\(\frac{9}{10}\)

Answer 3

\(\frac{1}{10}+\frac{12}{20}+\frac{3}{30}+\frac{4}{40}+\frac{5}{50}+\frac{6}{60}+\frac{7}{70}+\frac{8}{80}+\frac{9}{90}\)

\(=\frac{1}{10}+\frac{12}{20}+\frac{1}{10}+\frac{1}{10}+\frac{1}{10}+\frac{1}{10}+\frac{1}{10}+\frac{1}{10}+\frac{1}{10}\)

\(=\frac{1}{10}\times8+\frac{12}{20}\)

\(=\frac{4}{5}+\frac{12}{20}\)

\(=\frac{16}{20}+\frac{12}{20}=\frac{28}{20}=\frac{7}{5}\)