OK, let's crack this. We're given 949 and our task is to multiply it by 21. Essentially, we'll be adding 949 to itself 21 times.
Step 1: 0 + 949 = 949
Step 2: 949 + 949 = 1898
Step 3: 1898 + 949 = 2847
Step 4: 2847 + 949 = 3796
Step 5: 3796 + 949 = 4745
Step 6: 4745 + 949 = 5694
Step 7: 5694 + 949 = 6643
Step 8: 6643 + 949 = 7592
Step 9: 7592 + 949 = 8541
Step 10: 8541 + 949 = 9490
Step 11: 9490 + 949 = 10439
Step 12: 10439 + 949 = 11388
Step 13: 11388 + 949 = 12337
Step 14: 12337 + 949 = 13286
Step 15: 13286 + 949 = 14235
Step 16: 14235 + 949 = 15184
Step 17: 15184 + 949 = 16133
Step 18: 16133 + 949 = 17082
Step 19: 17082 + 949 = 18031
Step 20: 18031 + 949 = 18980
Step 21: 18980 + 949 = 19929

So, 949*21 = 19929