4.8× 5/4 + 1/4 = 41/4
5.6÷ 3/8 – 3/8 ÷6 = 255/16
6.4/7 × 5/9 + 3/7 × 5/9 = 5/9
7.5/2 -（ 3/2 + 4/5 ） = 1/5
8.7/8 + （ 1/8 + 1/9 ） = 10/9
9.9 × 5/6 + 5/6 = 25/3
10.3/4 × 8/9 - 1/3 = 1/3
11.7 × 5/49 + 3/14 = 13/14
12.6 ×（ 1/2 + 2/3 ）= 7
13.8 × 4/5 + 8 × 11/5 = 24
14.31 × 5/6 – 5/6 = 25
15.9/7 - （ 2/7 – 10/21 ）= 31/21
16.5/9 × 18 – 14 × 2/7 = 6
17.4/5 × 25/16 + 2/3 × 3/4 = 7/4
18.14 × 8/7 – 5/6 × 12/15 = 46/3
19.17/32 – 3/4 × 9/24 = 13/16
20.3 × 2/9 + 1/3 = 1
21.5/7 × 3/25 + 3/7 = 18/35
22.3/14 × 2/3 + 1/6 = 13/42
23.1/5 × 2/3 + 5/6 = 29/30
24.9/22 + 1/11 ÷ 1/2 = 13/22
25.5/3 × 11/5 + 4/3 = 5
26.45 × 2/3 + 1/3 × 15 = 35
27.7/19 + 12/19 × 5/6 = 17/19
28.1/4 + 3/4 ÷ 2/3 =11/8
29.8/7 × 21/16 + 1/2 = 2
30.101 × 1/5 – 1/5 × 21 = 16
31.50＋160÷40 （58+360）÷（64-45） = 138
32.120-144÷18+35 = 147
33.347+45×2-4160÷52 = 357
34（58+37）÷（64-9×5） = 5
35.95÷（64-45） = 5
36.178-145÷5×6+42 = 46
37.812-700÷（9+31×11）= 810
38.85+14×（14+208÷26） = 393
39.（284+16）×（512-8208÷18）= 16800
40.120-36×4÷18+35 = 147
41.（58+37）÷（64-9×5） = 5
42.(6.8-6.8×0.55)÷8.5 = 0.36
43.0.12× 4.8÷0.12×4.8 = 23.04
44.（3.2×1.5+2.5）÷1.6 = 4.5625
45.6-1.6÷4 = 5.6
46.7.2÷0.8-1.2×5 = 3
47.6.5×（4.8-1.2×4）= 0
48.10.15-10.75×0.4-5.7 = 0.15
49.5.8×（3.87-0.13）+4.2×3.74 = 37.4
50.32.52-（6+9.728÷3.2）×2.5 = 9.92
51.-5+58+13+90+78-(-56)+50 = 340
52.-7*2-57/3 = -33
53.(-7)*2/(1/3)+79/(3+6/4) = 59.556
54.123+456+789+98/(-4) = 1343.5
55.369/3-(-54-31/15.5) = 179
56.39+{3x[42/2x(3x8)]} = 1551
57.9x8x7/5x(4+6) = 1008
58.11x22/(4+12/2) = 24.2
59.94+(-60)/10 = 100
12*45+15*28+30*26+60*11
=12*15*3+15*28+2*15*26+15*4*11
=15*(12*3+28+26*2+4*11)
=15*160
=3*5*160
=800*3
=2400
197*198—196*199
=197*198-196*(198+1)
=197*198-196*198-196
=198*(197-196)-196
=198-196
=2
999×999+1999
=1000*999-999+1999
=999000+(1999-999)
=999000+1000
=1000000
：（100+99*1）+（99+99*2）+（98+99*3）+……+（2+99*99）+（1+99*100）
=(100+99+98+.+1)+99*1+99*2+99*3+.+99*100
=(100+1)*100/2+99*1+99*2+99*3+.+99*100
=5050+99*(1+2+3+...+100)
=5050+99*5050
=5050*(1+99)
=5050*100
=505000
9+99+999+……+8个9+9个9
=10+100+1000+...+1000000000-9
=1111111110-9
=1111111101
(1).(x+y-z)+(x-y+z)-(x-y-z)
=x+y-z+x-y+z-x+y+z
=x+y+z
(2).(a^2+2ab+b^2)-(a^2-2ab+b^2)
= a^2+2ab+b^2 - a^2+2ab-b^2
=4ab
(3).3(2x^2-y^2)-2(3y^2-2x^2)
=6x^2-3y^2-6y^2+4x^2
=10x^2-9y^2 4.8× 5/4 + 1/4 = 41/4
5.6÷ 3/8 – 3/8 ÷6 = 255/16
6.4/7 × 5/9 + 3/7 × 5/9 = 5/9
7.5/2 -（ 3/2 + 4/5 ） = 1/5
8.7/8 + （ 1/8 + 1/9 ） = 10/9
9.9 × 5/6 + 5/6 = 25/3
10.3/4 × 8/9 - 1/3 = 1/3
11.7 × 5/49 + 3/14 = 13/14
12.6 ×（ 1/2 + 2/3 ）= 7
13.8 × 4/5 + 8 × 11/5 = 24
14.31 × 5/6 – 5/6 = 25
15.9/7 - （ 2/7 – 10/21 ）= 31/21
16.5/9 × 18 – 14 × 2/7 = 6
17.4/5 × 25/16 + 2/3 × 3/4 = 7/4
18.14 × 8/7 – 5/6 × 12/15 = 46/3
19.17/32 – 3/4 × 9/24 = 13/16
20.3 × 2/9 + 1/3 = 1
21.5/7 × 3/25 + 3/7 = 18/35
22.3/14 × 2/3 + 1/6 = 13/42
23.1/5 × 2/3 + 5/6 = 29/30
24.9/22 + 1/11 ÷ 1/2 = 13/22
25.5/3 × 11/5 + 4/3 = 5
26.45 × 2/3 + 1/3 × 15 = 35
27.7/19 + 12/19 × 5/6 = 17/19
28.1/4 + 3/4 ÷ 2/3 =11/8
29.8/7 × 21/16 + 1/2 = 2
30.101 × 1/5 – 1/5 × 21 = 16
31.50＋160÷40 （58+360）÷（64-45） = 138
32.120-144÷18+35 = 147
33.347+45×2-4160÷52 = 357
34（58+37）÷（64-9×5） = 5
35.95÷（64-45） = 5
36.178-145÷5×6+42 = 46
37.812-700÷（9+31×11）= 810
38.85+14×（14+208÷26） = 393
39.（284+16）×（512-8208÷18）= 16800
40.120-36×4÷18+35 = 147
41.（58+37）÷（64-9×5） = 5
42.(6.8-6.8×0.55)÷8.5 = 0.36
43.0.12× 4.8÷0.12×4.8 = 23.04
44.（3.2×1.5+2.5）÷1.6 = 4.5625
45.6-1.6÷4 = 5.6
46.7.2÷0.8-1.2×5 = 3
47.6.5×（4.8-1.2×4）= 0
48.10.15-10.75×0.4-5.7 = 0.15
49.5.8×（3.87-0.13）+4.2×3.74 = 37.4
50.32.52-（6+9.728÷3.2）×2.5 = 9.92
51.-5+58+13+90+78-(-56)+50 = 340
52.-7*2-57/3 = -33
53.(-7)*2/(1/3)+79/(3+6/4) = 59.556
54.123+456+789+98/(-4) = 1343.5
55.369/3-(-54-31/15.5) = 179
56.39+{3x[42/2x(3x8)]} = 1551
57.9x8x7/5x(4+6) = 1008
58.11x22/(4+12/2) = 24.2
59.94+(-60)/10 = 100
12*45+15*28+30*26+60*11
=12*15*3+15*28+2*15*26+15*4*11
=15*(12*3+28+26*2+4*11)
=15*160
=3*5*160
=800*3
=2400
197*198—196*199
=197*198-196*(198+1)
=197*198-196*198-196
=198*(197-196)-196
=198-196
=2
999×999+1999
=1000*999-999+1999
=999000+(1999-999)
=999000+1000
=1000000
：（100+99*1）+（99+99*2）+（98+99*3）+……+（2+99*99）+（1+99*100）
=(100+99+98+.+1)+99*1+99*2+99*3+.+99*100
=(100+1)*100/2+99*1+99*2+99*3+.+99*100
=5050+99*(1+2+3+...+100)
=5050+99*5050
=5050*(1+99)
=5050*100
=505000
9+99+999+……+8个9+9个9
=10+100+1000+...+1000000000-9
=1111111110-9
=1111111101
(1).(x+y-z)+(x-y+z)-(x-y-z)
=x+y-z+x-y+z-x+y+z
=x+y+z
(2).(a^2+2ab+b^2)-(a^2-2ab+b^2)
= a^2+2ab+b^2 - a^2+2ab-b^2
=4ab
(3).3(2x^2-y^2)-2(3y^2-2x^2)
=6x^2-3y^2-6y^2+4x^2
=10x^2-9y^2