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(2) 既是 $2$ 的倍数,又是 $5$ 的倍数的最大三位数是(
① $999$ ② $995$ ③ $990$
③
)。① $999$ ② $995$ ③ $990$
答案
③
(3) 一个质数(
① 没有因数 ② 只有一个因数 ③ 只有两个因数
③
)。① 没有因数 ② 只有一个因数 ③ 只有两个因数
答案
③
(4) 下面各组数中,三个连续自然数都是合数的是(
① $14$ $15$ $16$ ② $7$ $8$ $9$ ③ $15$ $16$ $17$
①
)。① $14$ $15$ $16$ ② $7$ $8$ $9$ ③ $15$ $16$ $17$
答案
①
(5) $36÷1.2$ 的商(
① 小于 ② 大于 ③ 等于
①
)$36$。① 小于 ② 大于 ③ 等于
答案
①
(6) 两个乘数的积是 $21.6$,其中一个乘数是 $0.12$,另一个乘数是(
① $1.8$ ② $18$ ③ $180$
③
)。① $1.8$ ② $18$ ③ $180$
答案
③
(1) 直接写出得数。
$0.63÷7 = $
$3.6÷0.06 = $
$0.63÷7 = $
0.09
$0.56÷0.8 = $0.7
$0.2÷0.02 = $10
$1.25÷0.25 = $5
$3.6÷0.06 = $
60
$1÷0.25 = $4
$0.77÷11 = $0.07
$4.2÷3 = $1.4
答案
0.09；0.7；10；5；60；4；0.07；1.4
(2) 用竖式计算。(除不尽的得数保留两位小数。)
$102÷12 = $
$102÷12 = $
8.5
$0.675÷2.6\approx$0.26
$2.1÷0.56 = $3.75
答案
```
102÷12=8.5
8.5
12)102.0
96
---
60
60
---
0
0.675÷2.6≈0.26
0.259
26)6.750
5.2
---
1.55
1.30
---
0.250
0.234
---
0.016
2.1÷0.56=3.75
3.75
56)210.00
168
---
420
392
---
280
280
---
0
```
102÷12=8.5
8.5
12)102.0
96
---
60
60
---
0
0.675÷2.6≈0.26
0.259
26)6.750
5.2
---
1.55
1.30
---
0.250
0.234
---
0.016
2.1÷0.56=3.75
3.75
56)210.00
168
---
420
392
---
280
280
---
0
```
(3) 用递等式计算。(能简算的要简算。)
$1.35÷(1.35×0.8)$ $15×(0.15÷0.5)$ $1.53 + 23.4÷7.2$
$2.4×0.7÷2.4×0.7$ $3.45÷0.125÷0.8$ $47.8÷2.5÷47.8$
$1.35÷(1.35×0.8)$ $15×(0.15÷0.5)$ $1.53 + 23.4÷7.2$
$2.4×0.7÷2.4×0.7$ $3.45÷0.125÷0.8$ $47.8÷2.5÷47.8$
答案
1.
1.35÷(1.35×0.8)
=1.35÷1.35÷0.8
=1÷0.8
= 1.25
2.
15×(0.15÷0.5)
=15×0.3
= 4.5
3.
1.53 + 23.4÷7.2
=1.53 + 3.25
= 4.78
4.
2.4×0.7÷2.4×0.7
=2.4÷2.4×0.7×0.7
=1×0.7×0.7
= 0.49
5.
3.45÷0.125÷0.8
=3.45÷(0.125×0.8)
=3.45÷0.1
= 34.5
6.
47.8÷2.5÷47.8
=47.8÷47.8÷2.5
=1÷2.5
= 0.4
1.35÷(1.35×0.8)
=1.35÷1.35÷0.8
=1÷0.8
= 1.25
2.
15×(0.15÷0.5)
=15×0.3
= 4.5
3.
1.53 + 23.4÷7.2
=1.53 + 3.25
= 4.78
4.
2.4×0.7÷2.4×0.7
=2.4÷2.4×0.7×0.7
=1×0.7×0.7
= 0.49
5.
3.45÷0.125÷0.8
=3.45÷(0.125×0.8)
=3.45÷0.1
= 34.5
6.
47.8÷2.5÷47.8
=47.8÷47.8÷2.5
=1÷2.5
= 0.4
