Alright, let's solve this math problem step by step. First, we have the number 158. Next, we see the multiplication sign, which means we need to multiply something. And what are we multiplying it by? We multiply it by 90. So, we're going to take the number 158 and add it to itself 90 times.
Step 1: 0 + 158 = 158
Step 2: 158 + 158 = 316
Step 3: 316 + 158 = 474
Step 4: 474 + 158 = 632
Step 5: 632 + 158 = 790
Step 6: 790 + 158 = 948
Step 7: 948 + 158 = 1106
Step 8: 1106 + 158 = 1264
Step 9: 1264 + 158 = 1422
Step 10: 1422 + 158 = 1580
Step 11: 1580 + 158 = 1738
Step 12: 1738 + 158 = 1896
Step 13: 1896 + 158 = 2054
Step 14: 2054 + 158 = 2212
Step 15: 2212 + 158 = 2370
Step 16: 2370 + 158 = 2528
Step 17: 2528 + 158 = 2686
Step 18: 2686 + 158 = 2844
Step 19: 2844 + 158 = 3002
Step 20: 3002 + 158 = 3160
Step 21: 3160 + 158 = 3318
Step 22: 3318 + 158 = 3476
Step 23: 3476 + 158 = 3634
Step 24: 3634 + 158 = 3792
Step 25: 3792 + 158 = 3950
Step 26: 3950 + 158 = 4108
Step 27: 4108 + 158 = 4266
Step 28: 4266 + 158 = 4424
Step 29: 4424 + 158 = 4582
Step 30: 4582 + 158 = 4740
Step 31: 4740 + 158 = 4898
Step 32: 4898 + 158 = 5056
Step 33: 5056 + 158 = 5214
Step 34: 5214 + 158 = 5372
Step 35: 5372 + 158 = 5530
Step 36: 5530 + 158 = 5688
Step 37: 5688 + 158 = 5846
Step 38: 5846 + 158 = 6004
Step 39: 6004 + 158 = 6162
Step 40: 6162 + 158 = 6320
Step 41: 6320 + 158 = 6478
Step 42: 6478 + 158 = 6636
Step 43: 6636 + 158 = 6794
Step 44: 6794 + 158 = 6952
Step 45: 6952 + 158 = 7110
Step 46: 7110 + 158 = 7268
Step 47: 7268 + 158 = 7426
Step 48: 7426 + 158 = 7584
Step 49: 7584 + 158 = 7742
Step 50: 7742 + 158 = 7900
Step 51: 7900 + 158 = 8058
Step 52: 8058 + 158 = 8216
Step 53: 8216 + 158 = 8374
Step 54: 8374 + 158 = 8532
Step 55: 8532 + 158 = 8690
Step 56: 8690 + 158 = 8848
Step 57: 8848 + 158 = 9006
Step 58: 9006 + 158 = 9164
Step 59: 9164 + 158 = 9322
Step 60: 9322 + 158 = 9480
Step 61: 9480 + 158 = 9638
Step 62: 9638 + 158 = 9796
Step 63: 9796 + 158 = 9954
Step 64: 9954 + 158 = 10112
Step 65: 10112 + 158 = 10270
Step 66: 10270 + 158 = 10428
Step 67: 10428 + 158 = 10586
Step 68: 10586 + 158 = 10744
Step 69: 10744 + 158 = 10902
Step 70: 10902 + 158 = 11060
Step 71: 11060 + 158 = 11218
Step 72: 11218 + 158 = 11376
Step 73: 11376 + 158 = 11534
Step 74: 11534 + 158 = 11692
Step 75: 11692 + 158 = 11850
Step 76: 11850 + 158 = 12008
Step 77: 12008 + 158 = 12166
Step 78: 12166 + 158 = 12324
Step 79: 12324 + 158 = 12482
Step 80: 12482 + 158 = 12640
Step 81: 12640 + 158 = 12798
Step 82: 12798 + 158 = 12956
Step 83: 12956 + 158 = 13114
Step 84: 13114 + 158 = 13272
Step 85: 13272 + 158 = 13430
Step 86: 13430 + 158 = 13588
Step 87: 13588 + 158 = 13746
Step 88: 13746 + 158 = 13904
Step 89: 13904 + 158 = 14062
Step 90: 14062 + 158 = 14220

So, 158*90 = 14220