Note that parsing (X|HT)ML with regexes is fragile; you'd do better to use an XML parser, about which others can advise better than I. However:

c:\@Work\Perl\monks>perl -wMstrict -le
"use 5.010;
 ;;
 use Data::Dump qw(dd);
 ;;
 my $s = '<tr><td>99</td></tr><h3><table><tr>BBBBB 01/08/2018</h3>'
       . '<td>236</td><td>002</td><td>121</td><td>266</td></tr>'
       . '<tr><td>999</td><td>9999</td></tr>'
       ;
 print qq{[[$s]] \n};
 ;;
 my @n = $s =~ m{ (?: BBBBB [^>]+ > | \G) <td> (\d+) </td> }xmsg;
 dd \@n;
"
[[<tr><td>99</td></tr><h3><table><tr>BBBBB 01/08/2018</h3><td>236</td>
+<td>002</td><td>121</td><td>266</td></tr>
<tr><td>999</td><td>9999</td></tr>]]

[236, "002", 121, 266]
[download]

Update: A few afterthoughts:

• The  use 5.010; statement enforcing a minimum Perl version of 5.10.0 is not needed. I originally used a regex operator introduced with 5.10, but got rid of it, so you can lose the statement too.
• It might be wise to add more delimitation before and after the  BBBBB keying substring in the regex:
      m{ (?: <tr> BBBBB \b [^>]+ > | \G) <td> (\d+) </td> }xmsg
  This makes regex parsing of this HTML only slightly less problematic.
• Both these changes tested under Perl version 5.8.9.

---

Give a man a fish:  <%-{-{-{-<

---

In reply to Re: Regex help (updated) by AnomalousMonk
in thread Regex help 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! —
  • How do I compose an effective node title?
  • How do I post a question effectively?
  • Markup in the Monastery
• 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:
  	&		&
  	<		&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.