1 / 12

口算除法

口算除法. 1 、口算。. 20 × 4 = 80 ÷ 4 = 30 × 7 = 210 ÷ 7 = 40 × 5 = 200 ÷ 5 =. 20. 80. 210. 30. 200. 40. 2 、估算。. 81 ÷ 8 ≈ 122 ÷ 4 ≈. 10. 30. 120. 80. ， 又多买了 3 个气球。. 80÷20 =. 4 ( 个 ). 4 个 20 是 80. 即： 20×4=80 80÷20=4. 答：可以分给 4 个班。. 4 ( 个 ).

grace-wong
Download Presentation

口算除法

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. 口算除法

  2. 1、口算。 20 × 4 = 80 ÷ 4 = 30 × 7 = 210 ÷ 7 = 40 × 5 = 200 ÷ 5 = 20 80 210 30 200 40 2、估算。 81 ÷ 8 ≈ 122 ÷ 4 ≈ 10 30 120 80

  3. ，又多买了3个气球。 80÷20 = 4(个) 4个20是80 即：20×4=80 80÷20=4 答：可以分给4个班。 4(个) 83÷20≈ 80

  4. 80÷20 =4(个) 4个20是80 即：20×4=80 80÷20=4 答：可以分给4个班。 19 80÷19≈ 4(个) 20

  5. 3 2 60 ÷ 20 = 90 ÷ 30 = 80 ÷ 40= 3 3 3 2 62 ÷ 20 ≈ 93 ÷ 30 ≈ 80 ÷ 38≈ 60 90 40 口算除数是整十数的除法：先想被除数里面有几个十，除数是几个十，再根据乘法口诀，得出结果。 两位数除法的估算：一般是把两位数看作与它比较接近的整十数，再口算结果。

  6. 4 (个) 120÷30 = 答：可以分给4个班。 4 122 ÷ 30 ≈ 120 ÷ 28 ≈ 120 4 30

  7. 估算： 4 用四舍五入法把83看作80。 83÷20 ≈____ 122÷30 ≈____ 4 用四舍五入法把122看作120。 4 80÷19 ≈____ 用四舍五入法把19看作20。 6 240÷37 ≈____ 用四舍五入法把37看作40。 除法的估算：一般是把两位数或三位数看作与它比较接近的整十数或几百几十数，再口算结果。

  8. 口算下列各题 180÷30 = 240÷40 = 184÷30≈ 240÷37 ≈ 420÷60 = 420÷58 ≈ 6 6 6 6 7 7

  9. 70 30 60 20 小牛、小象、小狗、小马找妈妈。 240÷4 = 271÷9 ≈ 143÷7≈ 420÷6=

  10. 走入生活 1. P80的第2题。 2. P80的第5题。

  11. 阅读书本P78～P79，说说你的收获。

  12. 作业： P80练习十三第3、4题。

More Related