OK, let's crack this. We're given 777 and our task is to multiply it by 13. Essentially, we'll be adding 777 to itself 13 times.
Step 1: 0 + 777 = 777
Step 2: 777 + 777 = 1554
Step 3: 1554 + 777 = 2331
Step 4: 2331 + 777 = 3108
Step 5: 3108 + 777 = 3885
Step 6: 3885 + 777 = 4662
Step 7: 4662 + 777 = 5439
Step 8: 5439 + 777 = 6216
Step 9: 6216 + 777 = 6993
Step 10: 6993 + 777 = 7770
Step 11: 7770 + 777 = 8547
Step 12: 8547 + 777 = 9324
Step 13: 9324 + 777 = 10101

So, 777*13 = 10101