1. 直接写出得数。
15 + 1.5 =
6.3 + 1.8 =
3.6 + 6.34 =
9.8 - 2.28 - 6.72 =
7.6 - 0.9 =
3 ÷ 0.6 =
0.8 ÷ 0.25 =
0.9 × 1.1 ÷ 0.3 =
0.81 × 10 =
3.6 × 0.1 =
75 ÷ 2.5 =
1.8 ÷ 0.2 × 1.2 =
1.2 × 8 =
2.5 × 0.2 =
0.65 ÷ 0.13 =
17.6 + 2.4 ÷ 0.3 =
2.1 ÷ 0.7 =
5.8 ÷ 0.2 =
11.7 ÷ 0.3 =
4.3 + 4.21 - 0.21 =
0.36 × 2 =
7.2 ÷ 1.2 =
3.5 × 0.2 =
3.4 × 4 × 5 =
3.8 ÷ 0.2 =
0.81 ÷ 0.9 =
1.25 ÷ 0.25 =
101 × 3.21 - 3.21 =
9.6 ÷ 4.8 =
0.55 ÷ 0.11 =
10.1 × 0.4 =
6.4 × 0.1 ÷ 6.4 × 0.1 =

1. 16.5 8.1 9.94 0.8 6.7 5 3.2 3.3 8.1 0.36 30 10.8 9.6 0.5 5 25.6 3 29 39 8.3 0.72 6 0.7 68 19 0.9 5 321 2 5 4.04 0.01

2. 计算下面各题,能简算的要简算。
3.1 + 4.81 + 5.9 + 5.19
0.6 × (5.4 - 4.37 ÷ 2.3)
18 - (5.25 × 1.4 + 6.5)
7.67 ÷ 2.5 ÷ 0.4
0.9 × 2.35 + 0.9 × 3.35 - 1.7 × 0.9
30 × [7.5 ÷ (2.7 - 1.2)]

2. 19 2.1 4.15 7.67 3.6 150

3.1+4.81+5.9+5.19
=(3.1+5.9)+(4.81+5.19)
=9+10
=19
0.6×(5.4-4.37÷2.3)
=0.6×(5.4-1.9)
=0.6×3.5
=2.1
18-(5.25×1.4+6.5)
=18-(7.35+6.5)
=18-13.85
=4.15
7.67÷2.5÷0.4
=7.67÷(2.5×0.4)
=7.67÷1
=7.67
0.9×2.35+0.9×3.35-1.7×0.9
=0.9×(2.35+3.35-1.7)
=0.9×4
=3.6
30×[7.5÷(2.7-1.2)]
=30×[7.5÷1.5]
=30×5
=150

如果☆ + ○ = 100,那么☆×0.06 + ○×0.06 = ()；
如果☆×○ = 100,那么(☆×3.9)×○ = ()。

6 390

因为☆ + ○ = 100，所以☆×0.06 + ○×0.06 = (☆ + ○)×0.06 = 100×0.06 = 6；
因为☆×○ = 100，所以(☆×3.9)×○ = ☆×○×3.9 = 100×3.9 = 390。
6 390