Sure thing, let's get straight to it. We start with 712 and we're going to multiply it by 90, which means adding 712 to itself 90 times.
Step 1: 0 + 712 = 712
Step 2: 712 + 712 = 1424
Step 3: 1424 + 712 = 2136
Step 4: 2136 + 712 = 2848
Step 5: 2848 + 712 = 3560
Step 6: 3560 + 712 = 4272
Step 7: 4272 + 712 = 4984
Step 8: 4984 + 712 = 5696
Step 9: 5696 + 712 = 6408
Step 10: 6408 + 712 = 7120
Step 11: 7120 + 712 = 7832
Step 12: 7832 + 712 = 8544
Step 13: 8544 + 712 = 9256
Step 14: 9256 + 712 = 9968
Step 15: 9968 + 712 = 10680
Step 16: 10680 + 712 = 11392
Step 17: 11392 + 712 = 12104
Step 18: 12104 + 712 = 12816
Step 19: 12816 + 712 = 13528
Step 20: 13528 + 712 = 14240
Step 21: 14240 + 712 = 14952
Step 22: 14952 + 712 = 15664
Step 23: 15664 + 712 = 16376
Step 24: 16376 + 712 = 17088
Step 25: 17088 + 712 = 17800
Step 26: 17800 + 712 = 18512
Step 27: 18512 + 712 = 19224
Step 28: 19224 + 712 = 19936
Step 29: 19936 + 712 = 20648
Step 30: 20648 + 712 = 21360
Step 31: 21360 + 712 = 22072
Step 32: 22072 + 712 = 22784
Step 33: 22784 + 712 = 23496
Step 34: 23496 + 712 = 24208
Step 35: 24208 + 712 = 24920
Step 36: 24920 + 712 = 25632
Step 37: 25632 + 712 = 26344
Step 38: 26344 + 712 = 27056
Step 39: 27056 + 712 = 27768
Step 40: 27768 + 712 = 28480
Step 41: 28480 + 712 = 29192
Step 42: 29192 + 712 = 29904
Step 43: 29904 + 712 = 30616
Step 44: 30616 + 712 = 31328
Step 45: 31328 + 712 = 32040
Step 46: 32040 + 712 = 32752
Step 47: 32752 + 712 = 33464
Step 48: 33464 + 712 = 34176
Step 49: 34176 + 712 = 34888
Step 50: 34888 + 712 = 35600
Step 51: 35600 + 712 = 36312
Step 52: 36312 + 712 = 37024
Step 53: 37024 + 712 = 37736
Step 54: 37736 + 712 = 38448
Step 55: 38448 + 712 = 39160
Step 56: 39160 + 712 = 39872
Step 57: 39872 + 712 = 40584
Step 58: 40584 + 712 = 41296
Step 59: 41296 + 712 = 42008
Step 60: 42008 + 712 = 42720
Step 61: 42720 + 712 = 43432
Step 62: 43432 + 712 = 44144
Step 63: 44144 + 712 = 44856
Step 64: 44856 + 712 = 45568
Step 65: 45568 + 712 = 46280
Step 66: 46280 + 712 = 46992
Step 67: 46992 + 712 = 47704
Step 68: 47704 + 712 = 48416
Step 69: 48416 + 712 = 49128
Step 70: 49128 + 712 = 49840
Step 71: 49840 + 712 = 50552
Step 72: 50552 + 712 = 51264
Step 73: 51264 + 712 = 51976
Step 74: 51976 + 712 = 52688
Step 75: 52688 + 712 = 53400
Step 76: 53400 + 712 = 54112
Step 77: 54112 + 712 = 54824
Step 78: 54824 + 712 = 55536
Step 79: 55536 + 712 = 56248
Step 80: 56248 + 712 = 56960
Step 81: 56960 + 712 = 57672
Step 82: 57672 + 712 = 58384
Step 83: 58384 + 712 = 59096
Step 84: 59096 + 712 = 59808
Step 85: 59808 + 712 = 60520
Step 86: 60520 + 712 = 61232
Step 87: 61232 + 712 = 61944
Step 88: 61944 + 712 = 62656
Step 89: 62656 + 712 = 63368
Step 90: 63368 + 712 = 64080

So, 712*90 = 64080