Theorem 1p5e6

Description: 1 + 5 = 6. (Contributed by SN, 24-Aug-2026)

	Ref	Expression
Assertion	1p5e6	⊢ ( 1 + 5 ) = 6

Proof

Step	Hyp	Ref	Expression
1		df-5	⊢ 5 = ( 4 + 1 )
2	1	oveq2i	⊢ ( 1 + 5 ) = ( 1 + ( 4 + 1 ) )
3		ax-1cn	⊢ 1 ∈ ℂ
4		4cn	⊢ 4 ∈ ℂ
5	3 4 3	addassi	⊢ ( ( 1 + 4 ) + 1 ) = ( 1 + ( 4 + 1 ) )
6		1p4e5	⊢ ( 1 + 4 ) = 5
7	6	oveq1i	⊢ ( ( 1 + 4 ) + 1 ) = ( 5 + 1 )
8		5p1e6	⊢ ( 5 + 1 ) = 6
9	7 8	eqtri	⊢ ( ( 1 + 4 ) + 1 ) = 6
10	2 5 9	3eqtr2i	⊢ ( 1 + 5 ) = 6