OK, let's crack this. We're given 630 and our task is to multiply it by 45. Essentially, we'll be adding 630 to itself 45 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
Step 29: 17640 + 630 = 18270
Step 30: 18270 + 630 = 18900
Step 31: 18900 + 630 = 19530
Step 32: 19530 + 630 = 20160
Step 33: 20160 + 630 = 20790
Step 34: 20790 + 630 = 21420
Step 35: 21420 + 630 = 22050
Step 36: 22050 + 630 = 22680
Step 37: 22680 + 630 = 23310
Step 38: 23310 + 630 = 23940
Step 39: 23940 + 630 = 24570
Step 40: 24570 + 630 = 25200
Step 41: 25200 + 630 = 25830
Step 42: 25830 + 630 = 26460
Step 43: 26460 + 630 = 27090
Step 44: 27090 + 630 = 27720
Step 45: 27720 + 630 = 28350

So, 630*45 = 28350