Theorem 1p4e5

Description: 1 + 4 = 5. (Contributed by SN, 24-Aug-2026)

	Ref	Expression
Assertion	1p4e5	$$⊢1+4=5$$

Proof

Step	Hyp	Ref	Expression
1		df-4	$$⊢4=3+1$$
2	1	oveq2i	$$⊢1+4=1+3+1$$
3		ax-1cn	$$⊢1\in ℂ$$
4		3cn	$$⊢3\in ℂ$$
5	3 4 3	addassi	$$⊢1+3+1=1+3+1$$
6		1p3e4	$$⊢1+3=4$$
7	6	oveq1i	$$⊢1+3+1=4+1$$
8		4p1e5	$$⊢4+1=5$$
9	7 8	eqtri	$$⊢1+3+1=5$$
10	2 5 9	3eqtr2i	$$⊢1+4=5$$