Alright, let's solve this math problem step by step. First, we have the number 423. Next, we see the multiplication sign, which means we need to multiply something. And what are we multiplying it by? We multiply it by 66. So, we're going to take the number 423 and add it to itself 66 times.
Step 1: 0 + 423 = 423
Step 2: 423 + 423 = 846
Step 3: 846 + 423 = 1269
Step 4: 1269 + 423 = 1692
Step 5: 1692 + 423 = 2115
Step 6: 2115 + 423 = 2538
Step 7: 2538 + 423 = 2961
Step 8: 2961 + 423 = 3384
Step 9: 3384 + 423 = 3807
Step 10: 3807 + 423 = 4230
Step 11: 4230 + 423 = 4653
Step 12: 4653 + 423 = 5076
Step 13: 5076 + 423 = 5499
Step 14: 5499 + 423 = 5922
Step 15: 5922 + 423 = 6345
Step 16: 6345 + 423 = 6768
Step 17: 6768 + 423 = 7191
Step 18: 7191 + 423 = 7614
Step 19: 7614 + 423 = 8037
Step 20: 8037 + 423 = 8460
Step 21: 8460 + 423 = 8883
Step 22: 8883 + 423 = 9306
Step 23: 9306 + 423 = 9729
Step 24: 9729 + 423 = 10152
Step 25: 10152 + 423 = 10575
Step 26: 10575 + 423 = 10998
Step 27: 10998 + 423 = 11421
Step 28: 11421 + 423 = 11844
Step 29: 11844 + 423 = 12267
Step 30: 12267 + 423 = 12690
Step 31: 12690 + 423 = 13113
Step 32: 13113 + 423 = 13536
Step 33: 13536 + 423 = 13959
Step 34: 13959 + 423 = 14382
Step 35: 14382 + 423 = 14805
Step 36: 14805 + 423 = 15228
Step 37: 15228 + 423 = 15651
Step 38: 15651 + 423 = 16074
Step 39: 16074 + 423 = 16497
Step 40: 16497 + 423 = 16920
Step 41: 16920 + 423 = 17343
Step 42: 17343 + 423 = 17766
Step 43: 17766 + 423 = 18189
Step 44: 18189 + 423 = 18612
Step 45: 18612 + 423 = 19035
Step 46: 19035 + 423 = 19458
Step 47: 19458 + 423 = 19881
Step 48: 19881 + 423 = 20304
Step 49: 20304 + 423 = 20727
Step 50: 20727 + 423 = 21150
Step 51: 21150 + 423 = 21573
Step 52: 21573 + 423 = 21996
Step 53: 21996 + 423 = 22419
Step 54: 22419 + 423 = 22842
Step 55: 22842 + 423 = 23265
Step 56: 23265 + 423 = 23688
Step 57: 23688 + 423 = 24111
Step 58: 24111 + 423 = 24534
Step 59: 24534 + 423 = 24957
Step 60: 24957 + 423 = 25380
Step 61: 25380 + 423 = 25803
Step 62: 25803 + 423 = 26226
Step 63: 26226 + 423 = 26649
Step 64: 26649 + 423 = 27072
Step 65: 27072 + 423 = 27495
Step 66: 27495 + 423 = 27918

So, 423*66 = 27918