Metamath Proof Explorer


Definition df-2

Description: Define the number 2. (Contributed by NM, 27-May-1999)

Ref Expression
Assertion df-2 2 = 1 + 1

Detailed syntax breakdown

Step Hyp Ref Expression
0 c2 class 2
1 c1 class 1
2 caddc class +
3 1 1 2 co class 1 + 1
4 0 3 wceq wff 2 = 1 + 1