1五年級(jí)奧數(shù)題：小數(shù)的巧算(B)

1、小數(shù)的巧算A年級(jí)班 姓名得分一、填空題1.計(jì)算1.135+3.346+5.557+7.768+9.979= .2. 計(jì)算 1.996+19.97+199.8=.3. 計(jì)算9.8+99.8+999.8+9999.8+99999.8= .4. 計(jì)算 6.11+9.22+8.33+7.44+5.55+4.56+3.67+2.78+1.89=5. 計(jì)算1.1+3.3+5.5+7.7+9.9+11.11+13.13+15.15+17.17+19.19=6.計(jì)算2.894.68+4.686.11+4.68=7.計(jì)算17.4837-17.4819+17.4882=8.計(jì)算1.250.32 2.5=.9.計(jì)算

2、754.7+15.925=.10.計(jì)算28.6767+32 286.7+573.40.05=二、解答題11. 計(jì)算 172.46.2+2724 0.3812. 計(jì)算 0.00 0181 0.00 011963個(gè) 01028 個(gè) 013. 計(jì)算 12.34+23.45+34.56+45.67+56.78+67.89+ 78.91+89.12+91.2314. 下面有兩個(gè)小數(shù)：a=0.00 0105b=0.00 0191996 個(gè) 01994 個(gè) 0 求 a+b, a- b, a b, a b.答 案1. 27.7852. 221.766原式=(2-0.004)+(20-0.03)+(200-0.

3、2)=222-(0.004+0.03+0.2)=221.7663. 111109 提示: 仿上題.4. 49.555. 103.25原式=1.1 (1+3+ +9)+1.01(11+13+19)=1.1 25+1.01 75=103.256. 46.87. 1748原式=17.48 X 37-17.48 X 19+17.48 X 82=17.48 X (37-19+82)=17.48X100=17488. 1原式 =(1.25 0.8)(0.42.5)=1 1=19. 750原式 =75 4.7+5.3 (3 25)=75 (4.7+5.3) =75 10=75010. 2867原式 =28.

4、67 67+32 28.67+28.67 (20 0.05) =28.67 (67+32+1)=28.67 100 =286711. 原式=172.4 6.2+(1724+1000)0.38=172.46.2+1724 0.38+1000 0.38=172.46.2+172.4 3.8+380=172.4(6.2+3.8)+380=172.410+380=1724+380=210412. 181 是三位,11 是兩位,相乘后 181 11=1991 是四位,三位加兩位是五位,因此1991前面還要添一個(gè)0,又963+1028=1991所以個(gè) 01028 個(gè) 0 1992 個(gè) 00. 000181

5、 0.00 011=0.00 0199196313. 9 個(gè)加數(shù)中,十位、個(gè)位、十分位、百分位的數(shù)都是19，所以原式=11.11 (1+2+ +9)=11.1145=499.9514. a是小數(shù)點(diǎn)后有(1994+3-1=)1996位的小數(shù),b是小數(shù)點(diǎn)后有(1996+2-1= )1997 位小數(shù).a+b=0.00 01069a- b=0.00 010311994 個(gè) 01994 個(gè) 0a b=0.00 01995a b=1050 19=55?19小數(shù)的巧算(B)一、填空題1.計(jì)算 4.75-9.64+8.25-1.36=2.計(jì)算 3.71-2.74+4.7+5.29-0.26+6.3=.3.計(jì)算

6、(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+264 0.0625+5.26.25+0.6256.計(jì)算 0.035935+0.035+3 0.035+0.07 61 0.5=7.計(jì)算 19.9837-199.81.9+1998 0.82=.8.計(jì)算 13.59.9+6.510.仁9.計(jì)算 0.1250.25 0.5 64=.10.計(jì)算 11.843-860 0.09=.20=二、解答題11. 計(jì)算 32.14+64.280.5378 0.25+0.537864.28 0.75-864.280.125 0.5378.

7、12. 計(jì)算 0.888125 73+999 3.13. 計(jì)算 1998+199.8+19.98+1.998.b=0.00 082000 個(gè) 0 a b.14. 下面有兩個(gè)小數(shù)：a=0.00 0125'11996 個(gè) 0 試求 a+b, a-b, a b,答 案1. 2原式=(4.75+8.25 ) -(9.64+1.36)=13-11=22. 17原式=(3.71+5.29)+(4.7+6.3)-(2.74+0.26)=9+11-3=173. 89原式=(5.25+5.75+0.125)8=(11+0.125)8=11 8+0.125 8=88+仁894. 345原式=34.5 (8

8、.23+2.77-1)=34.510=3455. 62.5原式=6.25 0.16+2.646.25+5.26.25+6.252=6.25 (0.16+2.64+5.2+2)=6.25 10=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+6.5 0.1=135-1.35+65+0.65=(135+65)-(1.35-0.65)=200-0.7=199.39. 1原式=0.125 0.25 0.5 (8 4 2)=(0.1258) (0.25 4) (0.52)=1 1 1=110. 430原式

9、=11.8 43-43 20 0.09=11.8 43-43 1.8=43 (11.8-1.8)=4310=43011. 原式=32.14+64.28 0.5378 (0.25+0.75-80.125)=32.14+64.28 0.5378 0=32.1412. 原式=0.111 (8 125) 73+111 (9 3)=111 73+111 27=111 (73+27) =111 100=1110013. 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(duì)齊,然后按整數(shù)的加法法那么計(jì)算，所以a+b=0.00 012508 = 0.00 0125082000位 1996 '個(gè) 0a b,方法與a+b 一樣,數(shù)位對(duì)齊,還要注意退位和補(bǔ)零,因?yàn)閍=0.00 0125, b=0.00 08,由 12500-8=12492,所以1998 位 2000 位a- b=0.00 12492=