\(\begin{array}{l}
a)\,\,0,25 \times 1,25 \times 24 \times 8 \times 4\\
\,\,\,\,\,\, = \left( {0,25 \times 4} \right) \times \left( {1,25 \times 8} \right) \times 24\\
\,\,\,\,\,\, = 1 \times 10 \times 24\\
\,\,\,\,\,\, = 240\\
b)\,\,856 - 25,642 - 74,358\\
\,\,\,\,\,\, = 856 - \left( {25,642 + 74,358} \right)\\
\,\,\,\,\,\, = 856 - 98\\
\,\,\,\,\,\, = 758\\
c)\,\,\dfrac{{3,36 \times 0,2 \times 4 \times 19,8 \times 0,18:0,125}}{{1,12 \times 5 \times 6,6:0,25 \times 0,72 \times 16}}\\
\,\,\,\,\, = \dfrac{{3,36 \times 0,2 \times 4 \times 19,8 \times 0,18 \times 8}}{{1,12 \times 5 \times 6,6 \times 4 \times 0,72 \times 16}}\\
\,\,\,\,\, = \dfrac{{1,12 \times 3 \times 0,2 \times 4 \times 6,6 \times 3 \times 0,18 \times 8}}{{1,12 \times 5 \times 6,6 \times 4 \times 0,18 \times 4 \times 8 \times 2}}\\
\,\,\,\,\, = \dfrac{{3 \times 0,2 \times 3}}{{5 \times 4 \times 2}} = \dfrac{{3 \times 0,2 \times 3}}{{5 \times 4 \times 0,2 \times 10}}\\
\,\,\,\,\, = \dfrac{{3 \times 3}}{{5 \times 4 \times 10}} = \dfrac{9}{{200}}
\end{array}\)
Lưu ý : ta áp dụng công thức : \(a:0,125 = a\times 8 \;; \;\;\; a: 0,25 = a \times 4.\)
