Question

口算． 20 21 × 14 15 =	1 3 + 3 5 =	2 3 - 1 2 =
5 6 × 3 4 =	5 17 ×0=	4 5 × 5 8 =
4 9 ×2=	24× 3 8 =	9 14 × 7 6 =
8 9 × 5 12 =

Answer 1

分析：根據(jù)分?jǐn)?shù)乘法以及分?jǐn)?shù)加減法的計(jì)算法則求解即可．

解答：解：

20 21 × 14 15 = 8 9 ，	1 3 + 3 5 = 14 15 ，	2 3 - 1 2 = 1 6 ，
5 6 × 3 4 = 5 8 ，	5 17 ×0=0，	4 5 × 5 8 = 1 2 ，
4 9 ×2= 8 9 ，	24× 3 8 =9，	9 14 × 7 6 = 3 4 ．
8 9 × 5 12 = 10 27 ．

點(diǎn)評(píng)：本題考查了簡單的分?jǐn)?shù)加減法和分?jǐn)?shù)乘法的計(jì)算，計(jì)算時(shí)要細(xì)心，注意把結(jié)果化成最簡分?jǐn)?shù)．