Question

请帮忙把下面的七题的详细步骤写出来好吗？简便运算的，我急用！！！！！！！！

1.998+1246+9989

2.（8700+870+87）÷87

3. 125×8.8

4. 1.3+4.25+3.75+3.7

5. 17.15-（3.5-2.85）

6. 3.4×99+3.4

7.0.48÷(0.3×0.2+0.18)

Answer 1

1,998+1246+9989=1000-2+1000+246+10000-11=12233
2,(8700+870+87)/87=8700/87+870/87+87/87=111
3,125×8.8=152*(8+0.8)=125*8+125*0.8=1000+100=1100
4,1.3+4.25+3.75+3.7=(1.3+3.7)+(4.25+3.75)=5+8=13
5,17.15-（3.5-2.85）=17.15-3.5+2.85=17.15+2.85-3.5=16.5
6,3.4×99+3.4=3.4*(99+1)=3.4*100=340
7,0.48÷(0.3×0.2+0.18)=2

Answer 2

1. 998+1246+9989=(1000-2)+(1250-4)+(10000-11)=(1000+1250+10000)-(2+4+11)=12250-17=12233
2.（8700+870+87）÷87=8700÷87+870÷87+87÷87=100+10+1=111
3. 125×8.8=125×8+125×0.8=1000+100=1100
4. 1.3+4.25+3.75+3.7=（1.3+3.7）+（4.25+3.75）=5+8=13
5. 17.15-（3.5-2.85）=17.15+2.85-3.5=20-3.5=16.5
6. 3.4×99+3.4=3.4×（99+1）=340
7. 0.48÷(0.3×0.2+0.18)=0.48÷(0.06+0.18)=0.48÷0.24=2

Answer 3

998+1246+9989=998+2+9989+11+1233=11000+1233=12233
（8700+870+87）÷87=8700÷87+870÷87+87÷87=111
125×8.8=125×8+125×0.8=1000+100=1100
1.3+4.25+3.75+3.7=（1.3+3.7）+（4.25+3.75）=5+8=13
17.15-（3.5-2.85）=17.15+2.85-3.5=20-3.5=16.5
3.4×99+3.4=3.4×（99+1）=340
0.48÷(0.3×0.2+0.18)=0.48÷(0.06+0.18)=0.48÷0.24=2

Answer 4