38789

1. The pairs 9-1 8-2 7-3 6-4 work that leaves 10 and 5 10 because ten and zero is ten but there is no zero and 5 because double 5 is ten but there is only one 5
2. The pairs 10-2 9-3 8-4 7-5 work that leaves 1 and 6 6 because double six is 12 but there is only one six and 1 because 1 and eleven is twelve but there is no eleven
3. The pairs 10-3 9-4 8-5 7-6 work that leaves 1 and 2 1 because 1 and 12 is thirteen but there is no twelve and 2 because two and eleven is thirteen but there is no eleven
4. The pairs 10-1 9-2 8-3 7-4 6-5 work that leaves no so they all can be paired

Thank you for looking