That is a really good question. I did some experimenting and found it was the "0x<number>" construct that is causing it (the leading 0x is required). However, various experiments haven't revealed a pattern that I have noticed: 
print "0x1" + 0 = 1
print "0x2" + 0 = 1
print "0x3" + 0 = 1.5
print "0x4" + 0 = 1
print "0x5" + 0 = 1.25
print "0x6" + 0 = 1.5
print "0x7" + 0 = 1.75
print "0x8" + 0 = 1
print "0x9" + 0 = 1.125
print "0x10" + 0 = 1

[download]
And first glance, it would seem some sort of floating point conversion is going on, but exactly what, I don't know except that 9/8 = 1.125 (but why eight?) Actually, the following pattern exists: 
print "0x1" + 0 = 1          1/1     = 1
print "0x2" + 0 = 1          2/1     = 2
print "0x3" + 0 = 1.5        3/1.5   = 4
print "0x4" + 0 = 1          4/1     = 4
print "0x5" + 0 = 1.25       5/1.25  = 4
print "0x6" + 0 = 1.5        6/1.5   = 4
print "0x7" + 0 = 1.75       7/1.75  = 4 
print "0x8" + 0 = 1          8/1     = 8
print "0x9" + 0 = 1.125      9/1.125 = 8
print "0x10" + 0 = 1         10/1    = 10

[download]
0x01 is probably being interpreted as just a "0x1", whatever that is. Since all the results are on powers of 2 boundaries, I would presume some bit-oriented operation is happening.

Good question!

In reply to Re: Why are hex numbers inside strings extrapolating to numbers (incorrectly)? by mr.nick
in thread Why are hex numbers inside strings extrapolating to numbers (incorrectly)? by Anonymous Monk

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.