Alright, let's solve this math problem step by step. First, we have the number 280. Next, we see the multiplication sign, which means we need to multiply something. And what are we multiplying it by? We multiply it by 20. So, we're going to take the number 280 and add it to itself 20 times.
Step 1: 0 + 280 = 280
Step 2: 280 + 280 = 560
Step 3: 560 + 280 = 840
Step 4: 840 + 280 = 1120
Step 5: 1120 + 280 = 1400
Step 6: 1400 + 280 = 1680
Step 7: 1680 + 280 = 1960
Step 8: 1960 + 280 = 2240
Step 9: 2240 + 280 = 2520
Step 10: 2520 + 280 = 2800
Step 11: 2800 + 280 = 3080
Step 12: 3080 + 280 = 3360
Step 13: 3360 + 280 = 3640
Step 14: 3640 + 280 = 3920
Step 15: 3920 + 280 = 4200
Step 16: 4200 + 280 = 4480
Step 17: 4480 + 280 = 4760
Step 18: 4760 + 280 = 5040
Step 19: 5040 + 280 = 5320
Step 20: 5320 + 280 = 5600

So, 280*20 = 5600