OK, let's crack this. We're given 223 and our task is to multiply it by 21. Essentially, we'll be adding 223 to itself 21 times.
Step 1: 0 + 223 = 223
Step 2: 223 + 223 = 446
Step 3: 446 + 223 = 669
Step 4: 669 + 223 = 892
Step 5: 892 + 223 = 1115
Step 6: 1115 + 223 = 1338
Step 7: 1338 + 223 = 1561
Step 8: 1561 + 223 = 1784
Step 9: 1784 + 223 = 2007
Step 10: 2007 + 223 = 2230
Step 11: 2230 + 223 = 2453
Step 12: 2453 + 223 = 2676
Step 13: 2676 + 223 = 2899
Step 14: 2899 + 223 = 3122
Step 15: 3122 + 223 = 3345
Step 16: 3345 + 223 = 3568
Step 17: 3568 + 223 = 3791
Step 18: 3791 + 223 = 4014
Step 19: 4014 + 223 = 4237
Step 20: 4237 + 223 = 4460
Step 21: 4460 + 223 = 4683

So, 223*21 = 4683