問題
次の計算をしなさい.
解説
(1) $\, 31-12\div8\div(29-13\times2)\times18$
$29-13\times2=3$より,
$31-12\div8\div3\times18
=31-9
=$$22$となります.
(2) $\, 1.034\times7.3+4.71\times0.37-0.334\times7.3+2.29\times0.37$
$7.3$と$0.37$をそれぞれまとめると,
$(1.034-0.334)\times7.3+(4.71+2.29)\times0.37
=0.7\times7.3+7\times0.37$
$=0.7\times(7.3+3.7)
=$$7.7$となります.
(3) $\left(1\dfrac{1}{3}-0.6\right)\div \left\{ \dfrac{4}{63}\div\dfrac{2}{21} -\left(2\dfrac{3}{20}-0.55\right)\times0.375 \right\}$
$1\dfrac{1}{3}-0.6
=\dfrac{4}{3}-\dfrac{3}{5}
=\dfrac{11}{15}$
また,
$\dfrac{4}{63}\div\dfrac{2}{21}
=\dfrac{4}{63}\times\dfrac{21}{2}
=\dfrac{2}{3}$,
$\left(2\dfrac{3}{20}-0.55\right)\times0.375
=\left(\dfrac{43}{20}-\dfrac{11}{20}\right)\times\dfrac{3}{8}
=\dfrac{8}{5}\times\dfrac{3}{8}
=\dfrac{3}{5}$より,
$\dfrac{11}{15}\div
\left(\dfrac{2}{3}-\dfrac{3}{5}\right)
=\dfrac{11}{15}\div\dfrac{1}{15}
=$$11$となります.
