Question

Using all or some of the digits 2, 3, 4 and 5, Edward writes
numbers greater than 500 without repeating digits. For
example, he might write 543.
How many numbers does Edward write?

Answer 1

Using the digits 2,3,4 and 5, Edward wrote 28 numbers

Without repeating digits, we can stablish the next numbers greater than 500:

1. 534
2. 524
3. 532
4. 523
5. 2345
6. 2435
7. 2453
8. 2354
9. 2534
10. 2543
11. 3245
12. 3425
13. 3452
14. 3254
15. 3542
16. 3524
17. 4235
18. 4253
19. 4325
20. 4352
21. 4523
22. 4532
23. 5234
24. 5243
25. 5423
26. 5432
27. 5342
28. 5324