Let's get this math done. We have 877 and we're going to multiply it by 9. This is the same as taking 877 and adding it to itself 9 times.
Step 1: 0 + 877 = 877
Step 2: 877 + 877 = 1754
Step 3: 1754 + 877 = 2631
Step 4: 2631 + 877 = 3508
Step 5: 3508 + 877 = 4385
Step 6: 4385 + 877 = 5262
Step 7: 5262 + 877 = 6139
Step 8: 6139 + 877 = 7016
Step 9: 7016 + 877 = 7893

So, 877*9 = 7893