Metamath Proof Explorer
		
		
		
		Description:  Add a zero in the higher places.  (Contributed by Mario Carneiro, 18-Feb-2014)
		
			
				
					|  |  | Ref | Expression | 
					
						|  | Hypotheses | numnncl.1 |  | 
					
						|  |  | numnncl.2 |  | 
				
					|  | Assertion | num0h |  | 
			
		
		
			
				Proof
				
					
						| Step | Hyp | Ref | Expression | 
						
							| 1 |  | numnncl.1 |  | 
						
							| 2 |  | numnncl.2 |  | 
						
							| 3 | 1 | nn0cni |  | 
						
							| 4 | 3 | mul01i |  | 
						
							| 5 | 4 | oveq1i |  | 
						
							| 6 | 2 | nn0cni |  | 
						
							| 7 | 6 | addlidi |  | 
						
							| 8 | 5 7 | eqtr2i |  |