x
0
1
2
3
4
5
6
7
8
9
10
11
12
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
1
2
3
4
5
6
7
8
9
10
11
12
2
0
2
4
6
8
10
12
14
16
18
20
22
24
3
0
3
6
9
12
15
18
21
24
27
30
33
36
4
0
4
8
12
16
20
24
28
32
36
40
44
48
5
0
5
10
15
20
25
30
35
40
45
50
55
60
6
0
6
12
18
24
30
36
42
48
54
60
66
72
7
0
7
14
21
28
35
42
49
56
63
70
77
84
8
0
8
16
24
32
40
48
56
64
72
80
88
96
9
0
9
18
27
36
45
54
63
72
81
90
99
108
10
0
10
20
30
40
50
60
70
80
90
100
110
120
11
0
11
22
33
44
55
66
77
88
99
110
121
132
12
0
12
24
36
48
60
72
84
96
108
120
132
144

Why does 9 x 9 = 81?

Because adding 9 9's together makes 81.

That is, because 9 + 9 + 9 + 9 + 9 + 9 + 9 + 9 + 9 = 81.

Mathgrow

0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9