OK, let's crack this. We're given 667 and our task is to multiply it by 13. Essentially, we'll be adding 667 to itself 13 times.
Step 1: 0 + 667 = 667
Step 2: 667 + 667 = 1334
Step 3: 1334 + 667 = 2001
Step 4: 2001 + 667 = 2668
Step 5: 2668 + 667 = 3335
Step 6: 3335 + 667 = 4002
Step 7: 4002 + 667 = 4669
Step 8: 4669 + 667 = 5336
Step 9: 5336 + 667 = 6003
Step 10: 6003 + 667 = 6670
Step 11: 6670 + 667 = 7337
Step 12: 7337 + 667 = 8004
Step 13: 8004 + 667 = 8671

So, 667*13 = 8671