Metamath Proof Explorer
		
		
		
		Description:  The successor of a decimal integer (with carry).  (Contributed by Mario
       Carneiro, 18-Feb-2014)  (Revised by AV, 6-Sep-2021)
		
			
				
					|  |  | Ref | Expression | 
					
						|  | Hypotheses | decsucc.1 | ⊢ 𝐴  ∈  ℕ0 | 
					
						|  |  | decsucc.2 | ⊢ ( 𝐴  +  1 )  =  𝐵 | 
					
						|  |  | decsucc.3 | ⊢ 𝑁  =  ; 𝐴 9 | 
				
					|  | Assertion | decsucc | ⊢  ( 𝑁  +  1 )  =  ; 𝐵 0 | 
			
		
		
			
				Proof
				
					
						| Step | Hyp | Ref | Expression | 
						
							| 1 |  | decsucc.1 | ⊢ 𝐴  ∈  ℕ0 | 
						
							| 2 |  | decsucc.2 | ⊢ ( 𝐴  +  1 )  =  𝐵 | 
						
							| 3 |  | decsucc.3 | ⊢ 𝑁  =  ; 𝐴 9 | 
						
							| 4 |  | 9nn0 | ⊢ 9  ∈  ℕ0 | 
						
							| 5 |  | 9p1e10 | ⊢ ( 9  +  1 )  =  ; 1 0 | 
						
							| 6 | 5 | eqcomi | ⊢ ; 1 0  =  ( 9  +  1 ) | 
						
							| 7 |  | dfdec10 | ⊢ ; 𝐴 9  =  ( ( ; 1 0  ·  𝐴 )  +  9 ) | 
						
							| 8 | 3 7 | eqtri | ⊢ 𝑁  =  ( ( ; 1 0  ·  𝐴 )  +  9 ) | 
						
							| 9 | 4 6 1 2 8 | numsucc | ⊢ ( 𝑁  +  1 )  =  ( ( ; 1 0  ·  𝐵 )  +  0 ) | 
						
							| 10 |  | dfdec10 | ⊢ ; 𝐵 0  =  ( ( ; 1 0  ·  𝐵 )  +  0 ) | 
						
							| 11 | 9 10 | eqtr4i | ⊢ ( 𝑁  +  1 )  =  ; 𝐵 0 |