Metamath Proof Explorer


Theorem 2t2e4

Description: 2 times 2 equals 4. (Contributed by NM, 1-Aug-1999)

Ref Expression
Assertion 2t2e4 22=4

Proof

Step Hyp Ref Expression
1 2cn 2
2 1 2timesi 22=2+2
3 2p2e4 2+2=4
4 2 3 eqtri 22=4