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Description: Define the "decimal constructor", which is used to build up "decimal integers" or "numeric terms" in base 1 0 . For example, ( ; ; ; 1 0 0 0 + ; ; ; 2 0 0 0 ) = ; ; ; 3 0 0 0 1kp2ke3k . (Contributed by Mario Carneiro, 17-Apr-2015) (Revised by AV, 1-Aug-2021)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | df-dec | |- ; A B = ( ( ( 9 + 1 ) x. A ) + B ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 0 | cA | |- A |
|
| 1 | cB | |- B |
|
| 2 | 0 1 | cdc | |- ; A B |
| 3 | c9 | |- 9 |
|
| 4 | caddc | |- + |
|
| 5 | c1 | |- 1 |
|
| 6 | 3 5 4 | co | |- ( 9 + 1 ) |
| 7 | cmul | |- x. |
|
| 8 | 6 0 7 | co | |- ( ( 9 + 1 ) x. A ) |
| 9 | 8 1 4 | co | |- ( ( ( 9 + 1 ) x. A ) + B ) |
| 10 | 2 9 | wceq | |- ; A B = ( ( ( 9 + 1 ) x. A ) + B ) |