Let's get this math done. We have 901 and we're going to multiply it by 11. This is the same as taking 901 and adding it to itself 11 times.
Step 1: 0 + 901 = 901
Step 2: 901 + 901 = 1802
Step 3: 1802 + 901 = 2703
Step 4: 2703 + 901 = 3604
Step 5: 3604 + 901 = 4505
Step 6: 4505 + 901 = 5406
Step 7: 5406 + 901 = 6307
Step 8: 6307 + 901 = 7208
Step 9: 7208 + 901 = 8109
Step 10: 8109 + 901 = 9010
Step 11: 9010 + 901 = 9911

So, 901*11 = 9911