1. 分数乘法口诀
– 两数相乘：
– 2/3 4/5 = 8/15
– 3/4 6/7 = 9/28
– 5/6 8/9 = 20/54
– 三数相乘：
– 2/3 4/5 6/7 = 8/15 6/5 7/7 = 16/105
– 3/4 4/5 6/7 = 9/28 6/5 7/7 = 27/105
– 5/6 4/5 6/7 = 20/54 6/5 7/7 = 40/105
– 四数相乘：
– 2/3 4/5 6/7 8/9 = 8/15 6/5 7/7 8/9 = 16/105 6/5 7/7 8/9 = 24/105
– 3/4 4/5 6/7 8/9 = 9/28 6/5 7/7 8/9 = 27/105 6/5 7/7 8/9 = 40/105
– 5/6 4/5 6/7 8/9 = 20/54 6/5 7/7 8/9 = 40/105 6/5 7/7 8/9 = 56/105
2. 分数除法口诀
– 整数除以分数：
– 10/3 2/5 = 10/3 5/2 = 10 (5/2) = 10 2.5 = 25
– 12/4 3/5 = 12/4 5/3 = 12 (5/3) = 12 1.666… = 19.333…
– 分数除以分数：
– 2/3 4/5 = (2/3) (5/4) = (2 5)/(3 4) = (10)/(12) = 5/6
– 3/4 6/7 = (3/4) (7/6) = (3 7)/(4 6) = (21)/(24) = 7/8
– 小数除以分数：
– 0.5 / 2/3 = (0.5 3) / (2 2) = (1.5) / (4) = 0.375
3. 口诀记忆技巧
– 数字联想：将数字与分数联系起来，比如“一”对应“1”，”二”对应“2”，依此类推。
– 位置记忆：记住每个数字在分子和分母中的位置，这样计算时可以迅速定位。
– 分解记忆：将复杂的分数分解成更简单的部分，如“2/3”可以看作“2个1/3”。
– 练习应用：通过大量练习来巩固记忆，从简单到复杂逐步过渡。
掌握了这些口诀后，即使遇到不熟悉的分数，也能迅速找到对应的计算方法。
