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Metamath Proof Explorer

Theorem 9p8e17

Description: 9 + 8 = 17. (Contributed by Mario Carneiro, 19-Apr-2015)

		Ref	Expression
	Assertion	9p8e17	$⊢ 9 + 8 = 17$

Step	Hyp	Ref	Expression
1		9nn0	$⊢ 9 \in ℕ_{0}$
2		7nn0	$⊢ 7 \in ℕ_{0}$
3		6nn0	$⊢ 6 \in ℕ_{0}$
4		df-8	$⊢ 8 = 7 + 1$
5		df-7	$⊢ 7 = 6 + 1$
6		9p7e16	$⊢ 9 + 7 = 16$
7	1 2 3 4 5 6	6p5lem	$⊢ 9 + 8 = 17$