OK, let's work through this together. We're starting with 891 and we're going to multiply it by 12, which means we add 891 to itself 12 times.
Step 1: 0 + 891 = 891
Step 2: 891 + 891 = 1782
Step 3: 1782 + 891 = 2673
Step 4: 2673 + 891 = 3564
Step 5: 3564 + 891 = 4455
Step 6: 4455 + 891 = 5346
Step 7: 5346 + 891 = 6237
Step 8: 6237 + 891 = 7128
Step 9: 7128 + 891 = 8019
Step 10: 8019 + 891 = 8910
Step 11: 8910 + 891 = 9801
Step 12: 9801 + 891 = 10692

So, 891*12 = 10692