Addition -- Sums to 4
20 seconds
4
+ 0
0
1
2
3
4
2
+ 2
0
1
2
3
4
1
+ 1
0
1
2
3
4
0
+ 3
0
1
2
3
4
1
+ 3
0
1
2
3
4
0
+ 2
0
1
2
3
4
2
+ 2
0
1
2
3
4
0
+ 1
0
1
2
3
4
1
+ 3
0
1
2
3
4
4
+ 0
0
1
2
3
4
0
+ 1
0
1
2
3
4
0
+ 2
0
1
2
3
4
2
+ 2
0
1
2
3
4
0
+ 0
0
1
2
3
4
1
+ 0
0
1
2
3
4
4
+ 0
0
1
2
3
4
2
+ 0
0
1
2
3
4
2
+ 2
0
1
2
3
4
1
+ 3
0
1
2
3
4
0
+ 0
0
1
2
3
4
0
+ 2
0
1
2
3
4
2
+ 1
0
1
2
3
4
4
+ 0
0
1
2
3
4
3
+ 1
0
1
2
3
4
0
+ 1
0
1
2
3
4
2
+ 1
0
1
2
3
4
0
+ 0
0
1
2
3
4
1
+ 3
0
1
2
3
4
0
+ 1
0
1
2
3
4
0
+ 2
0
1
2
3
4
3
+ 1
0
1
2
3
4
0
+ 1
0
1
2
3
4
2
+ 2
0
1
2
3
4
0
+ 0
0
1
2
3
4
3
+ 1
0
1
2
3
4
1
+ 0
0
1
2
3
4
1
+ 1
0
1
2
3
4
4
+ 0
0
1
2
3
4
1
+ 3
0
1
2
3
4
2
+ 2
0
1
2
3
4
