OK, let's work through this together. We're starting with 144 and we're going to multiply it by 73, which means we add 144 to itself 73 times.
Step 1: 0 + 144 = 144
Step 2: 144 + 144 = 288
Step 3: 288 + 144 = 432
Step 4: 432 + 144 = 576
Step 5: 576 + 144 = 720
Step 6: 720 + 144 = 864
Step 7: 864 + 144 = 1008
Step 8: 1008 + 144 = 1152
Step 9: 1152 + 144 = 1296
Step 10: 1296 + 144 = 1440
Step 11: 1440 + 144 = 1584
Step 12: 1584 + 144 = 1728
Step 13: 1728 + 144 = 1872
Step 14: 1872 + 144 = 2016
Step 15: 2016 + 144 = 2160
Step 16: 2160 + 144 = 2304
Step 17: 2304 + 144 = 2448
Step 18: 2448 + 144 = 2592
Step 19: 2592 + 144 = 2736
Step 20: 2736 + 144 = 2880
Step 21: 2880 + 144 = 3024
Step 22: 3024 + 144 = 3168
Step 23: 3168 + 144 = 3312
Step 24: 3312 + 144 = 3456
Step 25: 3456 + 144 = 3600
Step 26: 3600 + 144 = 3744
Step 27: 3744 + 144 = 3888
Step 28: 3888 + 144 = 4032
Step 29: 4032 + 144 = 4176
Step 30: 4176 + 144 = 4320
Step 31: 4320 + 144 = 4464
Step 32: 4464 + 144 = 4608
Step 33: 4608 + 144 = 4752
Step 34: 4752 + 144 = 4896
Step 35: 4896 + 144 = 5040
Step 36: 5040 + 144 = 5184
Step 37: 5184 + 144 = 5328
Step 38: 5328 + 144 = 5472
Step 39: 5472 + 144 = 5616
Step 40: 5616 + 144 = 5760
Step 41: 5760 + 144 = 5904
Step 42: 5904 + 144 = 6048
Step 43: 6048 + 144 = 6192
Step 44: 6192 + 144 = 6336
Step 45: 6336 + 144 = 6480
Step 46: 6480 + 144 = 6624
Step 47: 6624 + 144 = 6768
Step 48: 6768 + 144 = 6912
Step 49: 6912 + 144 = 7056
Step 50: 7056 + 144 = 7200
Step 51: 7200 + 144 = 7344
Step 52: 7344 + 144 = 7488
Step 53: 7488 + 144 = 7632
Step 54: 7632 + 144 = 7776
Step 55: 7776 + 144 = 7920
Step 56: 7920 + 144 = 8064
Step 57: 8064 + 144 = 8208
Step 58: 8208 + 144 = 8352
Step 59: 8352 + 144 = 8496
Step 60: 8496 + 144 = 8640
Step 61: 8640 + 144 = 8784
Step 62: 8784 + 144 = 8928
Step 63: 8928 + 144 = 9072
Step 64: 9072 + 144 = 9216
Step 65: 9216 + 144 = 9360
Step 66: 9360 + 144 = 9504
Step 67: 9504 + 144 = 9648
Step 68: 9648 + 144 = 9792
Step 69: 9792 + 144 = 9936
Step 70: 9936 + 144 = 10080
Step 71: 10080 + 144 = 10224
Step 72: 10224 + 144 = 10368
Step 73: 10368 + 144 = 10512

So, 144*73 = 10512