Let's get this math done. We have 630 and we're going to multiply it by 28. This is the same as taking 630 and adding it to itself 28 times.
Step 1: 0 + 630 = 630
Step 2: 630 + 630 = 1260
Step 3: 1260 + 630 = 1890
Step 4: 1890 + 630 = 2520
Step 5: 2520 + 630 = 3150
Step 6: 3150 + 630 = 3780
Step 7: 3780 + 630 = 4410
Step 8: 4410 + 630 = 5040
Step 9: 5040 + 630 = 5670
Step 10: 5670 + 630 = 6300
Step 11: 6300 + 630 = 6930
Step 12: 6930 + 630 = 7560
Step 13: 7560 + 630 = 8190
Step 14: 8190 + 630 = 8820
Step 15: 8820 + 630 = 9450
Step 16: 9450 + 630 = 10080
Step 17: 10080 + 630 = 10710
Step 18: 10710 + 630 = 11340
Step 19: 11340 + 630 = 11970
Step 20: 11970 + 630 = 12600
Step 21: 12600 + 630 = 13230
Step 22: 13230 + 630 = 13860
Step 23: 13860 + 630 = 14490
Step 24: 14490 + 630 = 15120
Step 25: 15120 + 630 = 15750
Step 26: 15750 + 630 = 16380
Step 27: 16380 + 630 = 17010
Step 28: 17010 + 630 = 17640

So, 630*28 = 17640