Alright, let's solve this math problem step by step. First, we have the number 480. Next, we see the multiplication sign, which means we need to multiply something. And what are we multiplying it by? We multiply it by 21. So, we're going to take the number 480 and add it to itself 21 times.
Step 1: 0 + 480 = 480
Step 2: 480 + 480 = 960
Step 3: 960 + 480 = 1440
Step 4: 1440 + 480 = 1920
Step 5: 1920 + 480 = 2400
Step 6: 2400 + 480 = 2880
Step 7: 2880 + 480 = 3360
Step 8: 3360 + 480 = 3840
Step 9: 3840 + 480 = 4320
Step 10: 4320 + 480 = 4800
Step 11: 4800 + 480 = 5280
Step 12: 5280 + 480 = 5760
Step 13: 5760 + 480 = 6240
Step 14: 6240 + 480 = 6720
Step 15: 6720 + 480 = 7200
Step 16: 7200 + 480 = 7680
Step 17: 7680 + 480 = 8160
Step 18: 8160 + 480 = 8640
Step 19: 8640 + 480 = 9120
Step 20: 9120 + 480 = 9600
Step 21: 9600 + 480 = 10080

So, 480*21 = 10080