Let's roll up our sleeves and solve this. We have 145 and we're going to multiply it by 136, essentially adding 145 to itself 136 times.
Step 1: 0 + 145 = 145
Step 2: 145 + 145 = 290
Step 3: 290 + 145 = 435
Step 4: 435 + 145 = 580
Step 5: 580 + 145 = 725
Step 6: 725 + 145 = 870
Step 7: 870 + 145 = 1015
Step 8: 1015 + 145 = 1160
Step 9: 1160 + 145 = 1305
Step 10: 1305 + 145 = 1450
Step 11: 1450 + 145 = 1595
Step 12: 1595 + 145 = 1740
Step 13: 1740 + 145 = 1885
Step 14: 1885 + 145 = 2030
Step 15: 2030 + 145 = 2175
Step 16: 2175 + 145 = 2320
Step 17: 2320 + 145 = 2465
Step 18: 2465 + 145 = 2610
Step 19: 2610 + 145 = 2755
Step 20: 2755 + 145 = 2900
Step 21: 2900 + 145 = 3045
Step 22: 3045 + 145 = 3190
Step 23: 3190 + 145 = 3335
Step 24: 3335 + 145 = 3480
Step 25: 3480 + 145 = 3625
Step 26: 3625 + 145 = 3770
Step 27: 3770 + 145 = 3915
Step 28: 3915 + 145 = 4060
Step 29: 4060 + 145 = 4205
Step 30: 4205 + 145 = 4350
Step 31: 4350 + 145 = 4495
Step 32: 4495 + 145 = 4640
Step 33: 4640 + 145 = 4785
Step 34: 4785 + 145 = 4930
Step 35: 4930 + 145 = 5075
Step 36: 5075 + 145 = 5220
Step 37: 5220 + 145 = 5365
Step 38: 5365 + 145 = 5510
Step 39: 5510 + 145 = 5655
Step 40: 5655 + 145 = 5800
Step 41: 5800 + 145 = 5945
Step 42: 5945 + 145 = 6090
Step 43: 6090 + 145 = 6235
Step 44: 6235 + 145 = 6380
Step 45: 6380 + 145 = 6525
Step 46: 6525 + 145 = 6670
Step 47: 6670 + 145 = 6815
Step 48: 6815 + 145 = 6960
Step 49: 6960 + 145 = 7105
Step 50: 7105 + 145 = 7250
Step 51: 7250 + 145 = 7395
Step 52: 7395 + 145 = 7540
Step 53: 7540 + 145 = 7685
Step 54: 7685 + 145 = 7830
Step 55: 7830 + 145 = 7975
Step 56: 7975 + 145 = 8120
Step 57: 8120 + 145 = 8265
Step 58: 8265 + 145 = 8410
Step 59: 8410 + 145 = 8555
Step 60: 8555 + 145 = 8700
Step 61: 8700 + 145 = 8845
Step 62: 8845 + 145 = 8990
Step 63: 8990 + 145 = 9135
Step 64: 9135 + 145 = 9280
Step 65: 9280 + 145 = 9425
Step 66: 9425 + 145 = 9570
Step 67: 9570 + 145 = 9715
Step 68: 9715 + 145 = 9860
Step 69: 9860 + 145 = 10005
Step 70: 10005 + 145 = 10150
Step 71: 10150 + 145 = 10295
Step 72: 10295 + 145 = 10440
Step 73: 10440 + 145 = 10585
Step 74: 10585 + 145 = 10730
Step 75: 10730 + 145 = 10875
Step 76: 10875 + 145 = 11020
Step 77: 11020 + 145 = 11165
Step 78: 11165 + 145 = 11310
Step 79: 11310 + 145 = 11455
Step 80: 11455 + 145 = 11600
Step 81: 11600 + 145 = 11745
Step 82: 11745 + 145 = 11890
Step 83: 11890 + 145 = 12035
Step 84: 12035 + 145 = 12180
Step 85: 12180 + 145 = 12325
Step 86: 12325 + 145 = 12470
Step 87: 12470 + 145 = 12615
Step 88: 12615 + 145 = 12760
Step 89: 12760 + 145 = 12905
Step 90: 12905 + 145 = 13050
Step 91: 13050 + 145 = 13195
Step 92: 13195 + 145 = 13340
Step 93: 13340 + 145 = 13485
Step 94: 13485 + 145 = 13630
Step 95: 13630 + 145 = 13775
Step 96: 13775 + 145 = 13920
Step 97: 13920 + 145 = 14065
Step 98: 14065 + 145 = 14210
Step 99: 14210 + 145 = 14355
Step 100: 14355 + 145 = 14500
Step 101: 14500 + 145 = 14645
Step 102: 14645 + 145 = 14790
Step 103: 14790 + 145 = 14935
Step 104: 14935 + 145 = 15080
Step 105: 15080 + 145 = 15225
Step 106: 15225 + 145 = 15370
Step 107: 15370 + 145 = 15515
Step 108: 15515 + 145 = 15660
Step 109: 15660 + 145 = 15805
Step 110: 15805 + 145 = 15950
Step 111: 15950 + 145 = 16095
Step 112: 16095 + 145 = 16240
Step 113: 16240 + 145 = 16385
Step 114: 16385 + 145 = 16530
Step 115: 16530 + 145 = 16675
Step 116: 16675 + 145 = 16820
Step 117: 16820 + 145 = 16965
Step 118: 16965 + 145 = 17110
Step 119: 17110 + 145 = 17255
Step 120: 17255 + 145 = 17400
Step 121: 17400 + 145 = 17545
Step 122: 17545 + 145 = 17690
Step 123: 17690 + 145 = 17835
Step 124: 17835 + 145 = 17980
Step 125: 17980 + 145 = 18125
Step 126: 18125 + 145 = 18270
Step 127: 18270 + 145 = 18415
Step 128: 18415 + 145 = 18560
Step 129: 18560 + 145 = 18705
Step 130: 18705 + 145 = 18850
Step 131: 18850 + 145 = 18995
Step 132: 18995 + 145 = 19140
Step 133: 19140 + 145 = 19285
Step 134: 19285 + 145 = 19430
Step 135: 19430 + 145 = 19575
Step 136: 19575 + 145 = 19720

So, 145*136 = 19720