OK, let's crack this. We're given 907 and our task is to multiply it by 24. Essentially, we'll be adding 907 to itself 24 times.
Step 1: 0 + 907 = 907
Step 2: 907 + 907 = 1814
Step 3: 1814 + 907 = 2721
Step 4: 2721 + 907 = 3628
Step 5: 3628 + 907 = 4535
Step 6: 4535 + 907 = 5442
Step 7: 5442 + 907 = 6349
Step 8: 6349 + 907 = 7256
Step 9: 7256 + 907 = 8163
Step 10: 8163 + 907 = 9070
Step 11: 9070 + 907 = 9977
Step 12: 9977 + 907 = 10884
Step 13: 10884 + 907 = 11791
Step 14: 11791 + 907 = 12698
Step 15: 12698 + 907 = 13605
Step 16: 13605 + 907 = 14512
Step 17: 14512 + 907 = 15419
Step 18: 15419 + 907 = 16326
Step 19: 16326 + 907 = 17233
Step 20: 17233 + 907 = 18140
Step 21: 18140 + 907 = 19047
Step 22: 19047 + 907 = 19954
Step 23: 19954 + 907 = 20861
Step 24: 20861 + 907 = 21768

So, 907*24 = 21768