Alright, let's solve this math problem step by step. First, we have the number 347. 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 347 and add it to itself 21 times.
Step 1: 0 + 347 = 347
Step 2: 347 + 347 = 694
Step 3: 694 + 347 = 1041
Step 4: 1041 + 347 = 1388
Step 5: 1388 + 347 = 1735
Step 6: 1735 + 347 = 2082
Step 7: 2082 + 347 = 2429
Step 8: 2429 + 347 = 2776
Step 9: 2776 + 347 = 3123
Step 10: 3123 + 347 = 3470
Step 11: 3470 + 347 = 3817
Step 12: 3817 + 347 = 4164
Step 13: 4164 + 347 = 4511
Step 14: 4511 + 347 = 4858
Step 15: 4858 + 347 = 5205
Step 16: 5205 + 347 = 5552
Step 17: 5552 + 347 = 5899
Step 18: 5899 + 347 = 6246
Step 19: 6246 + 347 = 6593
Step 20: 6593 + 347 = 6940
Step 21: 6940 + 347 = 7287

So, 347*21 = 7287