OK, let's crack this. We're given 612 and our task is to multiply it by 35. Essentially, we'll be adding 612 to itself 35 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

So, 612*35 = 21420