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Metamath Proof Explorer

Theorem 8lt9

Description: 8 is less than 9. (Contributed by Mario Carneiro, 19-Feb-2014)

Ref Expression
Assertion 8lt9 8 < 9

Proof

Step Hyp Ref Expression
1 8re ⊢ 8 ∈ ℝ
2 1 ltp1i ⊢ 8 < ( 8 + 1 )
3 df-9 ⊢ 9 = ( 8 + 1 )
4 2 3 breqtrri ⊢ 8 < 9