Hãy tính: ​\(\displaystyle {1 \over 4} + {5 \over {12}} - {1 \over {13}} - {7 \over 8}\)

* Hướng dẫn giải

Ta có:

 \(\displaystyle {1 \over 4} + {5 \over {12}} - {1 \over {13}} - {7 \over 8}\)

\(\displaystyle = \dfrac{1.78}{{312}} + \dfrac{{5.26}}{{312}} - \dfrac{{1.24}}{{312}} - \dfrac{{7.39}}{{312}}\)

\(\displaystyle = {{78 + 130 - 24 - 273} \over {312}}\)

\(\displaystyle = {{ - 89} \over {312}}\)