小5算数　分数のいろいろな計算１１

めざせ！分数マスター！

分数のたし算ひき算，かけ算わり算を1問ずつ！

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＜問題＞

次の⑤～⑧の計算をしよう！

⑤　\(\displaystyle 3\frac{7}{3}+1\frac{3}{4}=\)

⑥　\(\displaystyle \frac{35}{6}÷15=\)

⑦　\(\displaystyle 3\frac{3}{4}-1.2=\)

⑧　\(\displaystyle 1\frac{5}{8}×28=\)

正解はこちら！

⑤　\(\displaystyle 3\frac{7}{3}+1\frac{3}{4}\)

\(\displaystyle =3\frac{7×4}{3×4}+1\frac{3×3}{4×3}\)

\(\displaystyle =3\frac{28}{12}+1\frac{9}{12}\)

\(\displaystyle =4\frac{37}{12}\)

\(\displaystyle =4\frac{1+12+12+12}{12}\)

\(\displaystyle =7\frac{1}{12}\)

⑥　\(\displaystyle \frac{35}{6}÷15\)

\(\displaystyle =\frac{35}{6×15}\)

\(\displaystyle =\frac{35}{90}\)

\(\displaystyle =\frac{7}{18}\)

⑦　\(\displaystyle 3\frac{3}{4}-1.2\)

\(\displaystyle =3\frac{3}{4}-\displaystyle \frac{12}{10}\)

\(\displaystyle =3\frac{3×5}{4×5}-\displaystyle \frac{12×2}{10×2}\)

\(\displaystyle =3\frac{15}{20}-\displaystyle \frac{24}{20}\)

\(\displaystyle =2\frac{15+20}{20}-\displaystyle \frac{24}{20}\)

\(\displaystyle =2\frac{35}{20}-\displaystyle \frac{24}{20}\)

\(\displaystyle =2\frac{11}{20}\)

⑧　\(\displaystyle 1\frac{5}{8}×28\)

\(\displaystyle =\frac{13}{8}×28\)

\(\displaystyle =\frac{13×28}{8}\)

\(\displaystyle =\frac{13×14}{4}\)

\(\displaystyle =\frac{13×7}{2}\)

\(\displaystyle =\frac{91}{2}\)　ここで終わってもOK！

\(\displaystyle =45\frac{1}{2}\)　帯分数にしてもOK！

全問解けたでしょうか？

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