I cannot verify that this would stop AutoPligg, but here's a quick solution to make the math question less bot readable:
Code:
{if isset($register_captcha_error)}<br /><span class="error">{$register_captcha_error}</span><br /><br />{/if}
<br />Answer the following: What is
{if $number1 eq 0}zero{elseif $number1 eq 1}one{elseif $number1 eq 2}two{elseif $number1 eq 3}three{elseif $number1 eq 4}four{elseif $number1 eq 5}five{elseif $number1 eq 6}six{elseif $number1 eq 7}seven{elseif $number1 eq 8}eight{elseif $number1 eq 9}nine{/if}
plus
{if $number2 eq 0}zero{elseif $number2 eq 1}one{elseif $number2 eq 2}two{elseif $number2 eq 3}three{elseif $number2 eq 4}four{elseif $number2 eq 5}five{elseif $number2 eq 6}six{elseif $number2 eq 7}seven{elseif $number2 eq 8}eight{elseif $number2 eq 9}nine{/if}
? <input type="text" size="2" name="answer" /><br /><br />
You can see it when registering at
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