五年級奧數(shù)題：小數(shù)的巧算(B)

1、精品好資料學(xué)習(xí)推薦一 小數(shù)的巧算（B）年級 班 姓名 得分 一、真空題 1. 計(jì)算4.75-9.64+8.25-1.36=_. 2. 計(jì)算3.17-2.74+4.7+5.29-0.26+6.3=_. 3. 計(jì)算(5.25+0.125+5.75)8=_. 4. 計(jì)算34.58.23-34.5+2.7734.5=_.5. 計(jì)算6.250.16+2640.0625+5.26.25+0.62520=_. 6. 計(jì)算0.035935+0.035+30.035+0.07610.5=_. 7. 計(jì)算 19.9837-199.81.9+19980.82=_. 8. 計(jì)算 13.59.9+6.510.1=_.

2、9. 計(jì)算 0.1250.250.564=_.10. 計(jì)算 11.843-8600.09=_.二、解答題11計(jì)算32.14+64.280.53780.25+0.537864.280.75-864.280.1250.5378.12. 計(jì)算 0.88812573+9993.13. 計(jì)算 1998+199.8+19.98+1.998.14. 下面有兩個小數(shù):a=0.000125 b=0.00081996個0 2000個0 試求a+b, a-b, ab, ab.答 案1. 2 原式=（4.75+8.25）-(9.64+1.36) =13-11 =2 2. 17 原式=(3.71+5.29)+(4.7+

3、6.3)-(2.74+0.26) =9+11-3 =17 3. 89 原式=(5.25+5.75+0.125)8 =(11+0.125)8 =118+0.1258 =88+1 =89 4. 345 原式=34.5(8.23+2.77-1) =34.510 =3455. 62.5原式=6.250.16+2.646.25+5.26.25+6.252 =6.25(0.16+2.64+5.2+2) =6.2510 =62.56. 357. 19988. 199.3 原式=13.5(10-0.1)+6.5(10+0.1) =13.510-13.50.1+6.510+6.50.1 =135-1.35+65

4、+0.65 =(135+65)-(1.35-0.65) =200-0.7 =199.39. 1 原式=0.1250.250.5(842) =(0.1258)(0.254)(0.52) =111 =110. 430 原式=11.843-43200.09 =11.843-431.8 =43(11.8-1.8) =4310 =43011.原式=32.14+64.280.5378(0.25+0.75-80.125) =32.14+64.280.53780 =32.1412. 原式=0.111(8125)73+111(93) =11173+11127 =111(73+27) =111100 =11100

5、13. 原式=(2000-2)+(200-0.2)+(20-0.02)+(2-0.002) =2222-2.222 =2222-(10-7.778) =2222-10+7.778 =2219.77814. a+b,a的小數(shù)點(diǎn)后面有1998位,b的小數(shù)點(diǎn)后面有2000位,小數(shù)加法要求數(shù)位對齊,然后按整數(shù)的加法法則計(jì)算,所以a+b=0.00012508 = 0.00012508 2000位 1996個0,方法與a+b一樣,數(shù)位對齊,還要注意退位和補(bǔ)零,因?yàn)閍=0.000125，b=0.0008,由12500-8=12492，所以1998位 2000位a-b=0.0012492=0.000124922000位 1996個0ab,ab的小數(shù)點(diǎn)后面應(yīng)該有1998+2000位,但1258=1000,所以ab=0