Sure thing! We've got 991 and we're gonna multiply it by 10. That's the same as adding 991 to itself 10 times.
Step 1: 0 + 991 = 991
Step 2: 991 + 991 = 1982
Step 3: 1982 + 991 = 2973
Step 4: 2973 + 991 = 3964
Step 5: 3964 + 991 = 4955
Step 6: 4955 + 991 = 5946
Step 7: 5946 + 991 = 6937
Step 8: 6937 + 991 = 7928
Step 9: 7928 + 991 = 8919
Step 10: 8919 + 991 = 9910

So, 991*10 = 9910