Wednesday, May 18, 2016

Rapid Math Tricks - Mathematical Curiosity #5

Finally digging out an old book out of the closet. I found this little math curiosity and decided to explore it further. 

12² = 144 while 21² = 441
13² = 169 while 31² = 961
112² = 12,544 while 211² = 44,521
...

function sqr($a) { return $a*$a}
function Rev($b) { return -join([System.Linq.Enumerable]::Reverse($b))}

for($i=0; $i -le 1000;$i++){$ir = [int]$(rev([string]$i));$s = sqr($i);$sir = sqr($ir);$rs = rev([string]$sir);if($rs -eq $s -and $i -ne $ir){write-host $i,$s,$ir,$sir }}

12 144 21 441
13 169 31 961
21 441 12 144
31 961 13 169
102 10404 201 40401
103 10609 301 90601
112 12544 211 44521
113 12769 311 96721
122 14884 221 48841
201 40401 102 10404
211 44521 112 12544
221 48841 122 14884
301 90601 103 10609
311 96721 113 12769

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