2005 PMWC Problems/Problem T10
Problem
Find the largest 12-digit number for which every two consecutive digits form a distinct 2-digit prime number.
Solution
We list all 2 digit primes:
11, 13, 17, 19
23, 29
31, 37
41, 43, 47
53, 59
61, 67
71, 73, 79
83, 89
97
Picking a 9 would get us:
97371311
So we pick an 8.
837319737131
That's the greatest.
See also
| 2005 PMWC (Problems) | ||
| Preceded by Problem T9 |
Followed by Last Question | |
| I: 1 • 2 • 3 • 4 • 5 • 6 • 7 • 8 • 9 • 10 • 11 • 12 • 13 • 14 • 15 T: 1 • 2 • 3 • 4 • 5 • 6 • 7 • 8 • 9 • 10 | ||
