Alright, let's solve this math problem step by step. First, we have the number 438. 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 438 and add it to itself 90 times.
Step 1: 0 + 438 = 438
Step 2: 438 + 438 = 876
Step 3: 876 + 438 = 1314
Step 4: 1314 + 438 = 1752
Step 5: 1752 + 438 = 2190
Step 6: 2190 + 438 = 2628
Step 7: 2628 + 438 = 3066
Step 8: 3066 + 438 = 3504
Step 9: 3504 + 438 = 3942
Step 10: 3942 + 438 = 4380
Step 11: 4380 + 438 = 4818
Step 12: 4818 + 438 = 5256
Step 13: 5256 + 438 = 5694
Step 14: 5694 + 438 = 6132
Step 15: 6132 + 438 = 6570
Step 16: 6570 + 438 = 7008
Step 17: 7008 + 438 = 7446
Step 18: 7446 + 438 = 7884
Step 19: 7884 + 438 = 8322
Step 20: 8322 + 438 = 8760
Step 21: 8760 + 438 = 9198
Step 22: 9198 + 438 = 9636
Step 23: 9636 + 438 = 10074
Step 24: 10074 + 438 = 10512
Step 25: 10512 + 438 = 10950
Step 26: 10950 + 438 = 11388
Step 27: 11388 + 438 = 11826
Step 28: 11826 + 438 = 12264
Step 29: 12264 + 438 = 12702
Step 30: 12702 + 438 = 13140
Step 31: 13140 + 438 = 13578
Step 32: 13578 + 438 = 14016
Step 33: 14016 + 438 = 14454
Step 34: 14454 + 438 = 14892
Step 35: 14892 + 438 = 15330
Step 36: 15330 + 438 = 15768
Step 37: 15768 + 438 = 16206
Step 38: 16206 + 438 = 16644
Step 39: 16644 + 438 = 17082
Step 40: 17082 + 438 = 17520
Step 41: 17520 + 438 = 17958
Step 42: 17958 + 438 = 18396
Step 43: 18396 + 438 = 18834
Step 44: 18834 + 438 = 19272
Step 45: 19272 + 438 = 19710
Step 46: 19710 + 438 = 20148
Step 47: 20148 + 438 = 20586
Step 48: 20586 + 438 = 21024
Step 49: 21024 + 438 = 21462
Step 50: 21462 + 438 = 21900
Step 51: 21900 + 438 = 22338
Step 52: 22338 + 438 = 22776
Step 53: 22776 + 438 = 23214
Step 54: 23214 + 438 = 23652
Step 55: 23652 + 438 = 24090
Step 56: 24090 + 438 = 24528
Step 57: 24528 + 438 = 24966
Step 58: 24966 + 438 = 25404
Step 59: 25404 + 438 = 25842
Step 60: 25842 + 438 = 26280
Step 61: 26280 + 438 = 26718
Step 62: 26718 + 438 = 27156
Step 63: 27156 + 438 = 27594
Step 64: 27594 + 438 = 28032
Step 65: 28032 + 438 = 28470
Step 66: 28470 + 438 = 28908
Step 67: 28908 + 438 = 29346
Step 68: 29346 + 438 = 29784
Step 69: 29784 + 438 = 30222
Step 70: 30222 + 438 = 30660
Step 71: 30660 + 438 = 31098
Step 72: 31098 + 438 = 31536
Step 73: 31536 + 438 = 31974
Step 74: 31974 + 438 = 32412
Step 75: 32412 + 438 = 32850
Step 76: 32850 + 438 = 33288
Step 77: 33288 + 438 = 33726
Step 78: 33726 + 438 = 34164
Step 79: 34164 + 438 = 34602
Step 80: 34602 + 438 = 35040
Step 81: 35040 + 438 = 35478
Step 82: 35478 + 438 = 35916
Step 83: 35916 + 438 = 36354
Step 84: 36354 + 438 = 36792
Step 85: 36792 + 438 = 37230
Step 86: 37230 + 438 = 37668
Step 87: 37668 + 438 = 38106
Step 88: 38106 + 438 = 38544
Step 89: 38544 + 438 = 38982
Step 90: 38982 + 438 = 39420

So, 438*90 = 39420