Alright, let's solve this math problem step by step. First, we have the number 690. Next, we see the multiplication sign, which means we need to multiply something. And what are we multiplying it by? We multiply it by 18. So, we're going to take the number 690 and add it to itself 18 times.
Step 1: 0 + 690 = 690
Step 2: 690 + 690 = 1380
Step 3: 1380 + 690 = 2070
Step 4: 2070 + 690 = 2760
Step 5: 2760 + 690 = 3450
Step 6: 3450 + 690 = 4140
Step 7: 4140 + 690 = 4830
Step 8: 4830 + 690 = 5520
Step 9: 5520 + 690 = 6210
Step 10: 6210 + 690 = 6900
Step 11: 6900 + 690 = 7590
Step 12: 7590 + 690 = 8280
Step 13: 8280 + 690 = 8970
Step 14: 8970 + 690 = 9660
Step 15: 9660 + 690 = 10350
Step 16: 10350 + 690 = 11040
Step 17: 11040 + 690 = 11730
Step 18: 11730 + 690 = 12420

So, 690*18 = 12420