一、在（ ）里填合适的数。
$6\times( ) = 18$ （ ）$\times8 = 8$ $21\div( ) = 7$
$100 + ( ) = 2100$ $24\div( ) = 4$ （ ）$- 200 = 30$
（ ）$\times7 = 49$ （ ）$+ 20 = 720$ $7\times( ) = 56$
$340 - ( ) = 300$ $36\div( ) = 4$ $500 + ( ) = 570$
$36\div( ) = 6$ $72\div( ) = 9$ $730 - ( ) = 30$
（ ）$\times3 = 9$ $5000 - ( ) = 2000$ （ ）$\div2 = 4$
$5\div( ) = 5$ （ ）$\times2 = 4$ $27\div( ) = 3$
（ ）$\div2 = 8$ （ ）$\div7 = 8$ （ ）$+ 200 = 4200$
$54\div( ) = 6$ $9\times( ) = 9$ $40\div( ) = 8$
$9\div( ) = 9$ （ ）$\div8 = 8$ $960 - ( ) = 900$
（ ）$\div7 = 5$ （ ）$\times5 = 45$ （ ）$\div9 = 7$
$2000 + ( ) = 4000$ （ ）$\div5 = 6$ $81\div( ) = 9$
（ ）$\div7 = 8\cdots\cdots4$ $55\div( ) = 8\cdots\cdots7$
（ ）$\div6 = 9\cdots\cdots5$ $49\div( ) = 6\cdots\cdots1$
（ ）$\div4 = 7\cdots\cdots3$ $25\div( ) = 4\cdots\cdots1$
（ ）$\div4 = 5\cdots\cdots2$ $46\div( ) = 5\cdots\cdots6$
（ ）$\div2 = 6\cdots\cdots1$ （ ）$\div3 = 4\cdots\cdots2$
（ ）$\div5 = 7\cdots\cdots4$ $42\div( ) = 8\cdots\cdots2$

3 1 3
2000 6 230
7 700 8
40 9 70
6 8 700
3 3000 8
1 2 9
16 56 4000
9 1 5
1 64 60
35 9 63
2000 30 9
60 6
59 8
31 6
22 8
13 14
39 5