OK, let's crack this. We're given 306 and our task is to multiply it by 99. Essentially, we'll be adding 306 to itself 99 times.
Step 1: 0 + 306 = 306
Step 2: 306 + 306 = 612
Step 3: 612 + 306 = 918
Step 4: 918 + 306 = 1224
Step 5: 1224 + 306 = 1530
Step 6: 1530 + 306 = 1836
Step 7: 1836 + 306 = 2142
Step 8: 2142 + 306 = 2448
Step 9: 2448 + 306 = 2754
Step 10: 2754 + 306 = 3060
Step 11: 3060 + 306 = 3366
Step 12: 3366 + 306 = 3672
Step 13: 3672 + 306 = 3978
Step 14: 3978 + 306 = 4284
Step 15: 4284 + 306 = 4590
Step 16: 4590 + 306 = 4896
Step 17: 4896 + 306 = 5202
Step 18: 5202 + 306 = 5508
Step 19: 5508 + 306 = 5814
Step 20: 5814 + 306 = 6120
Step 21: 6120 + 306 = 6426
Step 22: 6426 + 306 = 6732
Step 23: 6732 + 306 = 7038
Step 24: 7038 + 306 = 7344
Step 25: 7344 + 306 = 7650
Step 26: 7650 + 306 = 7956
Step 27: 7956 + 306 = 8262
Step 28: 8262 + 306 = 8568
Step 29: 8568 + 306 = 8874
Step 30: 8874 + 306 = 9180
Step 31: 9180 + 306 = 9486
Step 32: 9486 + 306 = 9792
Step 33: 9792 + 306 = 10098
Step 34: 10098 + 306 = 10404
Step 35: 10404 + 306 = 10710
Step 36: 10710 + 306 = 11016
Step 37: 11016 + 306 = 11322
Step 38: 11322 + 306 = 11628
Step 39: 11628 + 306 = 11934
Step 40: 11934 + 306 = 12240
Step 41: 12240 + 306 = 12546
Step 42: 12546 + 306 = 12852
Step 43: 12852 + 306 = 13158
Step 44: 13158 + 306 = 13464
Step 45: 13464 + 306 = 13770
Step 46: 13770 + 306 = 14076
Step 47: 14076 + 306 = 14382
Step 48: 14382 + 306 = 14688
Step 49: 14688 + 306 = 14994
Step 50: 14994 + 306 = 15300
Step 51: 15300 + 306 = 15606
Step 52: 15606 + 306 = 15912
Step 53: 15912 + 306 = 16218
Step 54: 16218 + 306 = 16524
Step 55: 16524 + 306 = 16830
Step 56: 16830 + 306 = 17136
Step 57: 17136 + 306 = 17442
Step 58: 17442 + 306 = 17748
Step 59: 17748 + 306 = 18054
Step 60: 18054 + 306 = 18360
Step 61: 18360 + 306 = 18666
Step 62: 18666 + 306 = 18972
Step 63: 18972 + 306 = 19278
Step 64: 19278 + 306 = 19584
Step 65: 19584 + 306 = 19890
Step 66: 19890 + 306 = 20196
Step 67: 20196 + 306 = 20502
Step 68: 20502 + 306 = 20808
Step 69: 20808 + 306 = 21114
Step 70: 21114 + 306 = 21420
Step 71: 21420 + 306 = 21726
Step 72: 21726 + 306 = 22032
Step 73: 22032 + 306 = 22338
Step 74: 22338 + 306 = 22644
Step 75: 22644 + 306 = 22950
Step 76: 22950 + 306 = 23256
Step 77: 23256 + 306 = 23562
Step 78: 23562 + 306 = 23868
Step 79: 23868 + 306 = 24174
Step 80: 24174 + 306 = 24480
Step 81: 24480 + 306 = 24786
Step 82: 24786 + 306 = 25092
Step 83: 25092 + 306 = 25398
Step 84: 25398 + 306 = 25704
Step 85: 25704 + 306 = 26010
Step 86: 26010 + 306 = 26316
Step 87: 26316 + 306 = 26622
Step 88: 26622 + 306 = 26928
Step 89: 26928 + 306 = 27234
Step 90: 27234 + 306 = 27540
Step 91: 27540 + 306 = 27846
Step 92: 27846 + 306 = 28152
Step 93: 28152 + 306 = 28458
Step 94: 28458 + 306 = 28764
Step 95: 28764 + 306 = 29070
Step 96: 29070 + 306 = 29376
Step 97: 29376 + 306 = 29682
Step 98: 29682 + 306 = 29988
Step 99: 29988 + 306 = 30294

So, 306*99 = 30294