小学奥数题及答案(9)

原式=6.25 0.16+2.64 6.25+5.2 6.25+6.25 2

=6.25 (0.16+2.64+5.2+2)

=6.25 10

=62.5

6. 35

7. 1998

8. 199.3

原式=13.5 (10-0.1)+6.5 (10+0.1)

=13.5 10-13.5 0.1+6.5 10+6.5 0.1

=135-1.35+65+0.65

=(135+65)-(1.35-0.65)

=200-0.7

=199.3

9. 1

原式=0.125 0.25 0.5 (8 4 2)

=(0.125 8) (0.25 4) (0.5 2)

=1 1 1

=1

10. 430

原式=11.8 43-43 20 0.09

=11.8 43-43 1.8

=43 (11.8-1.8)

=43 10

=430

11.

原式=32.14+64.28 0.5378 (0.25+0.75-8 0.125)

=32.14+64.28 0.5378 0

=32.14

12.

原式=0.111 (8 125) 73+111 (9 3)

=111 73+111 27

=111 (73+27)

=111 100

=11100

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

=2219.778

14. a+b,a的小数点后面有1998位,b的小数点后面有2000位,小数加法要求数位对齐,然后按整数的加法法则计算,所以

a+b=0.00 012508 = 0.00 012508

2000位 1996个0

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