Alright, let's solve this math problem step by step. First, we have the number 890. 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 890 and add it to itself 20 times.
Step 1: 0 + 890 = 890
Step 2: 890 + 890 = 1780
Step 3: 1780 + 890 = 2670
Step 4: 2670 + 890 = 3560
Step 5: 3560 + 890 = 4450
Step 6: 4450 + 890 = 5340
Step 7: 5340 + 890 = 6230
Step 8: 6230 + 890 = 7120
Step 9: 7120 + 890 = 8010
Step 10: 8010 + 890 = 8900
Step 11: 8900 + 890 = 9790
Step 12: 9790 + 890 = 10680
Step 13: 10680 + 890 = 11570
Step 14: 11570 + 890 = 12460
Step 15: 12460 + 890 = 13350
Step 16: 13350 + 890 = 14240
Step 17: 14240 + 890 = 15130
Step 18: 15130 + 890 = 16020
Step 19: 16020 + 890 = 16910
Step 20: 16910 + 890 = 17800

So, 890*20 = 17800