Let's roll up our sleeves and solve this. We have 907 and we're going to multiply it by 13, essentially adding 907 to itself 13 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

So, 907*13 = 11791