OK, let's crack this. We're given 616 and our task is to multiply it by 90. Essentially, we'll be adding 616 to itself 90 times.
Step 1: 0 + 616 = 616
Step 2: 616 + 616 = 1232
Step 3: 1232 + 616 = 1848
Step 4: 1848 + 616 = 2464
Step 5: 2464 + 616 = 3080
Step 6: 3080 + 616 = 3696
Step 7: 3696 + 616 = 4312
Step 8: 4312 + 616 = 4928
Step 9: 4928 + 616 = 5544
Step 10: 5544 + 616 = 6160
Step 11: 6160 + 616 = 6776
Step 12: 6776 + 616 = 7392
Step 13: 7392 + 616 = 8008
Step 14: 8008 + 616 = 8624
Step 15: 8624 + 616 = 9240
Step 16: 9240 + 616 = 9856
Step 17: 9856 + 616 = 10472
Step 18: 10472 + 616 = 11088
Step 19: 11088 + 616 = 11704
Step 20: 11704 + 616 = 12320
Step 21: 12320 + 616 = 12936
Step 22: 12936 + 616 = 13552
Step 23: 13552 + 616 = 14168
Step 24: 14168 + 616 = 14784
Step 25: 14784 + 616 = 15400
Step 26: 15400 + 616 = 16016
Step 27: 16016 + 616 = 16632
Step 28: 16632 + 616 = 17248
Step 29: 17248 + 616 = 17864
Step 30: 17864 + 616 = 18480
Step 31: 18480 + 616 = 19096
Step 32: 19096 + 616 = 19712
Step 33: 19712 + 616 = 20328
Step 34: 20328 + 616 = 20944
Step 35: 20944 + 616 = 21560
Step 36: 21560 + 616 = 22176
Step 37: 22176 + 616 = 22792
Step 38: 22792 + 616 = 23408
Step 39: 23408 + 616 = 24024
Step 40: 24024 + 616 = 24640
Step 41: 24640 + 616 = 25256
Step 42: 25256 + 616 = 25872
Step 43: 25872 + 616 = 26488
Step 44: 26488 + 616 = 27104
Step 45: 27104 + 616 = 27720
Step 46: 27720 + 616 = 28336
Step 47: 28336 + 616 = 28952
Step 48: 28952 + 616 = 29568
Step 49: 29568 + 616 = 30184
Step 50: 30184 + 616 = 30800
Step 51: 30800 + 616 = 31416
Step 52: 31416 + 616 = 32032
Step 53: 32032 + 616 = 32648
Step 54: 32648 + 616 = 33264
Step 55: 33264 + 616 = 33880
Step 56: 33880 + 616 = 34496
Step 57: 34496 + 616 = 35112
Step 58: 35112 + 616 = 35728
Step 59: 35728 + 616 = 36344
Step 60: 36344 + 616 = 36960
Step 61: 36960 + 616 = 37576
Step 62: 37576 + 616 = 38192
Step 63: 38192 + 616 = 38808
Step 64: 38808 + 616 = 39424
Step 65: 39424 + 616 = 40040
Step 66: 40040 + 616 = 40656
Step 67: 40656 + 616 = 41272
Step 68: 41272 + 616 = 41888
Step 69: 41888 + 616 = 42504
Step 70: 42504 + 616 = 43120
Step 71: 43120 + 616 = 43736
Step 72: 43736 + 616 = 44352
Step 73: 44352 + 616 = 44968
Step 74: 44968 + 616 = 45584
Step 75: 45584 + 616 = 46200
Step 76: 46200 + 616 = 46816
Step 77: 46816 + 616 = 47432
Step 78: 47432 + 616 = 48048
Step 79: 48048 + 616 = 48664
Step 80: 48664 + 616 = 49280
Step 81: 49280 + 616 = 49896
Step 82: 49896 + 616 = 50512
Step 83: 50512 + 616 = 51128
Step 84: 51128 + 616 = 51744
Step 85: 51744 + 616 = 52360
Step 86: 52360 + 616 = 52976
Step 87: 52976 + 616 = 53592
Step 88: 53592 + 616 = 54208
Step 89: 54208 + 616 = 54824
Step 90: 54824 + 616 = 55440

So, 616*90 = 55440