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]