Tính bằng cách thuận tiện

a) \(\frac{{250}}{{1000}} + \frac{{469}}{{1000}} + \frac{{150}}{{1000}}\)

= \(\left( {\frac{{250}}{{1000}} + \frac{{150}}{{1000}}} \right) + \frac{{469}}{{1000}}\)

= \(\frac{{400}}{{1000}} + \frac{{469}}{{1000}}\)

= \(\frac{{869}}{{1000}}\)

b) \(\frac{{35}}{{12}} + \frac{{18}}{{24}} + \frac{2}{{24}}\)

= \(\frac{{35}}{{12}} + \left( {\frac{{18}}{{24}} + \frac{2}{{24}}} \right)\)

= \(\frac{{35}}{{12}} + \frac{{10}}{{12}}\)

= \(\frac{{45}}{{12}}\)

= \(\frac{{15}}{4}\)