Description: 9 times 8 equals 72. (Contributed by Mario Carneiro, 19-Apr-2015)
Ref | Expression | ||
---|---|---|---|
Assertion | 9t8e72 | |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | 9nn0 | |
|
2 | 7nn0 | |
|
3 | df-8 | |
|
4 | 9t7e63 | |
|
5 | 6nn0 | |
|
6 | 3nn0 | |
|
7 | eqid | |
|
8 | 6p1e7 | |
|
9 | 2nn0 | |
|
10 | 9cn | |
|
11 | 3cn | |
|
12 | 9p3e12 | |
|
13 | 10 11 12 | addcomli | |
14 | 5 6 1 7 8 9 13 | decaddci | |
15 | 1 2 3 4 14 | 4t3lem | |