OK, let's crack this. We're given 612 and our task is to multiply it by 109. Essentially, we'll be adding 612 to itself 109 times.
Step 1: 0 + 612 = 612
Step 2: 612 + 612 = 1224
Step 3: 1224 + 612 = 1836
Step 4: 1836 + 612 = 2448
Step 5: 2448 + 612 = 3060
Step 6: 3060 + 612 = 3672
Step 7: 3672 + 612 = 4284
Step 8: 4284 + 612 = 4896
Step 9: 4896 + 612 = 5508
Step 10: 5508 + 612 = 6120
Step 11: 6120 + 612 = 6732
Step 12: 6732 + 612 = 7344
Step 13: 7344 + 612 = 7956
Step 14: 7956 + 612 = 8568
Step 15: 8568 + 612 = 9180
Step 16: 9180 + 612 = 9792
Step 17: 9792 + 612 = 10404
Step 18: 10404 + 612 = 11016
Step 19: 11016 + 612 = 11628
Step 20: 11628 + 612 = 12240
Step 21: 12240 + 612 = 12852
Step 22: 12852 + 612 = 13464
Step 23: 13464 + 612 = 14076
Step 24: 14076 + 612 = 14688
Step 25: 14688 + 612 = 15300
Step 26: 15300 + 612 = 15912
Step 27: 15912 + 612 = 16524
Step 28: 16524 + 612 = 17136
Step 29: 17136 + 612 = 17748
Step 30: 17748 + 612 = 18360
Step 31: 18360 + 612 = 18972
Step 32: 18972 + 612 = 19584
Step 33: 19584 + 612 = 20196
Step 34: 20196 + 612 = 20808
Step 35: 20808 + 612 = 21420
Step 36: 21420 + 612 = 22032
Step 37: 22032 + 612 = 22644
Step 38: 22644 + 612 = 23256
Step 39: 23256 + 612 = 23868
Step 40: 23868 + 612 = 24480
Step 41: 24480 + 612 = 25092
Step 42: 25092 + 612 = 25704
Step 43: 25704 + 612 = 26316
Step 44: 26316 + 612 = 26928
Step 45: 26928 + 612 = 27540
Step 46: 27540 + 612 = 28152
Step 47: 28152 + 612 = 28764
Step 48: 28764 + 612 = 29376
Step 49: 29376 + 612 = 29988
Step 50: 29988 + 612 = 30600
Step 51: 30600 + 612 = 31212
Step 52: 31212 + 612 = 31824
Step 53: 31824 + 612 = 32436
Step 54: 32436 + 612 = 33048
Step 55: 33048 + 612 = 33660
Step 56: 33660 + 612 = 34272
Step 57: 34272 + 612 = 34884
Step 58: 34884 + 612 = 35496
Step 59: 35496 + 612 = 36108
Step 60: 36108 + 612 = 36720
Step 61: 36720 + 612 = 37332
Step 62: 37332 + 612 = 37944
Step 63: 37944 + 612 = 38556
Step 64: 38556 + 612 = 39168
Step 65: 39168 + 612 = 39780
Step 66: 39780 + 612 = 40392
Step 67: 40392 + 612 = 41004
Step 68: 41004 + 612 = 41616
Step 69: 41616 + 612 = 42228
Step 70: 42228 + 612 = 42840
Step 71: 42840 + 612 = 43452
Step 72: 43452 + 612 = 44064
Step 73: 44064 + 612 = 44676
Step 74: 44676 + 612 = 45288
Step 75: 45288 + 612 = 45900
Step 76: 45900 + 612 = 46512
Step 77: 46512 + 612 = 47124
Step 78: 47124 + 612 = 47736
Step 79: 47736 + 612 = 48348
Step 80: 48348 + 612 = 48960
Step 81: 48960 + 612 = 49572
Step 82: 49572 + 612 = 50184
Step 83: 50184 + 612 = 50796
Step 84: 50796 + 612 = 51408
Step 85: 51408 + 612 = 52020
Step 86: 52020 + 612 = 52632
Step 87: 52632 + 612 = 53244
Step 88: 53244 + 612 = 53856
Step 89: 53856 + 612 = 54468
Step 90: 54468 + 612 = 55080
Step 91: 55080 + 612 = 55692
Step 92: 55692 + 612 = 56304
Step 93: 56304 + 612 = 56916
Step 94: 56916 + 612 = 57528
Step 95: 57528 + 612 = 58140
Step 96: 58140 + 612 = 58752
Step 97: 58752 + 612 = 59364
Step 98: 59364 + 612 = 59976
Step 99: 59976 + 612 = 60588
Step 100: 60588 + 612 = 61200
Step 101: 61200 + 612 = 61812
Step 102: 61812 + 612 = 62424
Step 103: 62424 + 612 = 63036
Step 104: 63036 + 612 = 63648
Step 105: 63648 + 612 = 64260
Step 106: 64260 + 612 = 64872
Step 107: 64872 + 612 = 65484
Step 108: 65484 + 612 = 66096
Step 109: 66096 + 612 = 66708

So, 612*109 = 66708