神机妙算(能简算的要写出简算过程)(1)4113×34+5114×45+6115×56+7116×67+8117×78+9118×89(2)25×16%+114×21.75+114+2÷45+2.5÷322(3)517-23×2514÷[(3112+4.375)÷1989](4)已知-数学
9 |
8 |
8 |
9 |
=30+1+40+1+50+1+60+1+70+1+80+1,
=(30+40+50+60+70+80)+(1×6),
=330+6,
=336;
(2)25×16%-
1
| ||
1.75+1
|
4 |
5 |
3 |
22 |
=25×16%-2.5÷3+2÷
4 |
5 |
3 |
22 |
=2.5×1.6+2.5×
1 |
3 |
22 |
3 |
=2.5×(1.6+1-
1 |
3 |
22 |
3 |
=2.5×9.6,
=24;
(3)5
1 |
7 |
2 |
3 |
5 |
14 |
1 |
12 |
8 |
9 |
=5
1 |
7 |
2 |
3 |
5 |
14 |
11 |
24 |
8 |
9 |
=5