Let's get this math done. We have 505 and we're going to multiply it by 51. This is the same as taking 505 and adding it to itself 51 times.
Step 1: 0 + 505 = 505
Step 2: 505 + 505 = 1010
Step 3: 1010 + 505 = 1515
Step 4: 1515 + 505 = 2020
Step 5: 2020 + 505 = 2525
Step 6: 2525 + 505 = 3030
Step 7: 3030 + 505 = 3535
Step 8: 3535 + 505 = 4040
Step 9: 4040 + 505 = 4545
Step 10: 4545 + 505 = 5050
Step 11: 5050 + 505 = 5555
Step 12: 5555 + 505 = 6060
Step 13: 6060 + 505 = 6565
Step 14: 6565 + 505 = 7070
Step 15: 7070 + 505 = 7575
Step 16: 7575 + 505 = 8080
Step 17: 8080 + 505 = 8585
Step 18: 8585 + 505 = 9090
Step 19: 9090 + 505 = 9595
Step 20: 9595 + 505 = 10100
Step 21: 10100 + 505 = 10605
Step 22: 10605 + 505 = 11110
Step 23: 11110 + 505 = 11615
Step 24: 11615 + 505 = 12120
Step 25: 12120 + 505 = 12625
Step 26: 12625 + 505 = 13130
Step 27: 13130 + 505 = 13635
Step 28: 13635 + 505 = 14140
Step 29: 14140 + 505 = 14645
Step 30: 14645 + 505 = 15150
Step 31: 15150 + 505 = 15655
Step 32: 15655 + 505 = 16160
Step 33: 16160 + 505 = 16665
Step 34: 16665 + 505 = 17170
Step 35: 17170 + 505 = 17675
Step 36: 17675 + 505 = 18180
Step 37: 18180 + 505 = 18685
Step 38: 18685 + 505 = 19190
Step 39: 19190 + 505 = 19695
Step 40: 19695 + 505 = 20200
Step 41: 20200 + 505 = 20705
Step 42: 20705 + 505 = 21210
Step 43: 21210 + 505 = 21715
Step 44: 21715 + 505 = 22220
Step 45: 22220 + 505 = 22725
Step 46: 22725 + 505 = 23230
Step 47: 23230 + 505 = 23735
Step 48: 23735 + 505 = 24240
Step 49: 24240 + 505 = 24745
Step 50: 24745 + 505 = 25250
Step 51: 25250 + 505 = 25755

So, 505*51 = 25755