【小学6年算数】3-2 分数と分数のかけ算｜問題集

Q: 分数と分数のかけ算はどうやって解きますか？

分子同士、分母同士をかけて計算します。帯分数は仮分数に直してから計算するとわかりやすいです。

Q: 約分はいつ行うべきですか？

計算の途中でも後でも構いませんが、計算の前に約分しておくとミスが減り計算も簡単になります。

Q: 帯分数のかけ算で気をつけることは？

帯分数は必ず仮分数に直してから計算しましょう。直さないと計算ミスにつながります。

Question 1

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

Answer

\(\displaystyle \frac{4}{21}\)

Question 2

(2)\(\displaystyle \frac{5}{9}×\frac{3}{8}\)

Answer

\(\displaystyle \frac{5}{24}\)

Question 3

(3)\(\displaystyle \frac{7}{12}×\frac{8}{21}\)

Answer

\(\displaystyle \frac{2}{9}\)

Question 4

(4)\(\displaystyle \frac{5}{24}×\frac{12}{35}\)

Answer

\(\displaystyle \frac{1}{14}\)

Question 5

(5)\(\displaystyle 1\frac{1}{2}×\frac{3}{5}\)

Answer

\(\displaystyle \frac{9}{10}\)

Question 6

(6)\(\displaystyle 2\frac{1}{3}×1\frac{3}{7}\)

Answer

\(\displaystyle \frac{10}{3}\)

Question 7

(7)\(\displaystyle \frac{2}{5}×\frac{4}{3}\)

Answer

\(\displaystyle \frac{8}{15}\)

Question 8

(8)\(\displaystyle \frac{2}{9}×\frac{1}{3}\)

Answer

\(\displaystyle \frac{2}{27}\)

Question 9

(9)\(\displaystyle \frac{1}{3}×\frac{7}{6}\)

Answer

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

Question 10

(10)\(\displaystyle 1\frac{1}{5}×2\frac{2}{7}\)

Answer

\(\displaystyle \frac{96}{35}\)

Question 11

(11)\(\displaystyle 3\frac{1}{2}×1\frac{2}{5}\)

Answer

\(\displaystyle \frac{49}{10}\)

Question 12

(12)\(\displaystyle 1\frac{1}{6}×1\frac{2}{9}\)

Answer

\(\displaystyle \frac{77}{54}\)

Question 13

(13)\(\displaystyle \frac{3}{28}×\frac{7}{9}\)

Answer

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

Question 14

(14)\(\displaystyle \frac{2}{8}×\frac{3}{9}\)

Answer

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

Question 15

(15)\(\displaystyle \frac{9}{14}×\frac{2}{3}\)

Answer

\(\displaystyle \frac{3}{7}\)

Question 16

(16)\(\displaystyle \frac{3}{5}×\frac{5}{6}×\frac{5}{7}\)

Answer

\(\displaystyle \frac{5}{14}\)

Question 17

(17)\(\displaystyle \frac{5}{6}×\frac{9}{10}×\frac{1}{7}\)

Answer

\(\displaystyle \frac{3}{28}\)

Question 18

(18)\(\displaystyle \frac{1}{5}×\frac{3}{8}×\frac{4}{9}\)

Answer

\(\displaystyle \frac{1}{30}\)

Question 19

(19)\(\displaystyle \frac{1}{6}×\frac{3}{7}×\frac{7}{8}\)

Answer

\(\displaystyle \frac{1}{16}\)

Question 20

(20)\(\displaystyle 1\frac{1}{4}×\frac{2}{3}\)

Answer

\(\displaystyle \frac{5}{6}\)

Question 21

(21)\(\displaystyle 1\frac{3}{8}×\frac{4}{5}\)

Answer

\(\displaystyle \frac{11}{10}\)

Question 22

(22)\(\displaystyle 5\frac{1}{4}×1\frac{7}{9}\)

Answer

\(\displaystyle \frac{28}{3}\)

Question 23

(23)\(\displaystyle 6×\frac{5}{9}×\frac{2}{3}\)

Answer

\(\displaystyle \frac{20}{9}\)

Question 24

(24)\(\displaystyle 2\frac{2}{5}×1\frac{1}{6}\)

Answer

\(\displaystyle \frac{14}{5}\)

Question 25

(25)\(\displaystyle 1\frac{1}{3}×2\frac{5}{2}\)

Question 26

(26)\(\displaystyle \frac{2}{7}×1\frac{2}{5}\)

Answer

\(\displaystyle \frac{2}{5}\)

Question 27

(27)\(\displaystyle \frac{8}{9}×1\frac{3}{8}\)

Answer

\(\displaystyle \frac{11}{9}\)

Question 28

(28)\(\displaystyle 12×\frac{5}{6}×\frac{2}{3}\)

Answer

\(\displaystyle \frac{20}{3}\)

Question 29

(29)\(\displaystyle 1\frac{1}{3}×1\frac{1}{5}\)

Answer

\(\displaystyle \frac{8}{5}\)

Question 30

(30)\(\displaystyle \frac{2}{9}×2×\frac{3}{8}\)

Answer

\(\displaystyle \frac{1}{6}\)

Question 31

(1)\(1dℓ\)で\(\displaystyle \frac{4}{5}\)m\(^2\)の壁を塗れるペンキがある。このペンキが\(\displaystyle \frac{12}{7}dℓ\)あるとき、何m\(^2\)の壁が塗れるか答えなさい。

Answer

\(\displaystyle \frac{4}{5}×\frac{12}{7}=\frac{48}{35}\)
【答】\(\displaystyle \frac{48}{35}\)m\(^2\)

Question 32

(2)\(1\)mで\(\displaystyle 1\frac{6}{7}\)kgの棒がある。この棒が\(\displaystyle 2\frac{3}{8}\)mあるとき、重さは何kgになるか答えなさい。

Answer

\(\displaystyle 1\frac{6}{7}×2\frac{3}{8}=\frac{247}{56}\)
【答】\(\displaystyle \frac{247}{56}\)kg

Question 33

(3)\(1\)mで\(\displaystyle \frac{8}{9}\)kgのパイプがある。このパイプが\(\displaystyle \frac{21}{16}\)mあるとき、パイプの重さは何kgになるか答えなさい。

Answer

\(\displaystyle \frac{8}{9}×\frac{21}{16}=\frac{7}{6}\)
【答】\(\displaystyle \frac{7}{6}\)kg

Question 34

(4)\(1ℓ\)で\(\displaystyle 1\frac{5}{7}\)kgの小豆がある。この小豆が\(\displaystyle 3\frac{4}{15}ℓ\)あるとき、重さは何kgになるか答えなさい。

Answer

\(\displaystyle 1\frac{5}{7}×3\frac{4}{15}=\frac{28}{5}\)
【答】\(\displaystyle \frac{28}{5}\)kg

Question 35

(5)底辺が\(\displaystyle 1\frac{9}{16}\)cm、高さが\(\displaystyle 2\frac{2}{15}\)cmの平行四辺形の面積は何cm\(^2\)になるか答えなさい。

Answer

\(\displaystyle 1\frac{9}{16}×2\frac{2}{15}=\frac{10}{3}\)
【答】\(\displaystyle \frac{10}{3}\)cm\(^2\)

Question 36

(6)縦が\(\displaystyle 1\frac{5}{8}\)cm、横が\(\displaystyle 2\frac{4}{13}\)cmの長方形の面積は何cm\(^2\)になるか答えなさい。

Answer

\(\displaystyle 1\frac{5}{8}×2\frac{4}{13}=\frac{15}{4}\)
【答】\(\displaystyle \frac{15}{4}\)cm\(^2\)

Question 37

(7)\(1ℓ\)のガソリンで\(\displaystyle 8\frac{4}{7}\)km走るバイクがある。\(\displaystyle 5\frac{2}{15}ℓ\)のガソリンで、何km走ることができるか答えなさい。

Answer

\(\displaystyle 8\frac{4}{7}×5\frac{2}{15}=44\)
【答】\(44\)km

Question 38

(8)縦が\(\displaystyle \frac{2}{3}\)m、横が\(\displaystyle \frac{3}{5}\)m、高さが\(\displaystyle \frac{7}{8}\)mの直方体の体積を求めなさい。

Answer

\(\displaystyle \frac{2}{3}×\frac{3}{5}×\frac{7}{8}=\frac{7}{20}\)
【答】\(\displaystyle \frac{7}{20}\)m\(^3\)

Question 39

(1)\(\displaystyle \left(\frac{2}{5}+\frac{3}{10}\right)×10\)

Question 40

(2)\(\displaystyle \left(\frac{7}{8}-\frac{3}{4}\right)×8\)

Question 41

(3)\(\displaystyle 8×\left(\frac{3}{4}+\frac{5}{2}\right)\)

Question 42

(4)\(\displaystyle 9×\left(\frac{2}{3}-\frac{4}{9}\right)\)

Question 43

(5)\(\displaystyle \frac{5}{14}×12+\frac{9}{14}×12\)

Question 44

(6)\(\displaystyle \frac{17}{10}×15-\frac{7}{10}×15\)

Question 45

(7)\(\displaystyle 8×\frac{7}{11}+8×\frac{4}{11}\)

Question 46

(8)\(\displaystyle 9×\frac{9}{7}-\frac{2}{7}×9\)