I have this form which calculates a golf handicap, and it works like a charm, but...

But if a user doesn't actually hit all the keys on the keyboard it doesn't calculate right...

Lets say a user has handicap 16,3 and he insert this number in the form the calculation on the fly gives him example 19, but next time he uses this, when he hits "1" the input field pops up with the suggestion of his last insert, and then the user uses the mouse to click on the suggested number, the calculation only sees the "1" and not the rest and that way calculates wrong...

My question is how to get rit of this auto suggestion for that specific field?

Thanks in advance....
PHP Code:
echo '<input type="hidden" name="handicapindex" onKeyup="coursehcp(this);'.$matchCalc.'gir_calc();" class="h_index" value="'.$handicapindex.'">'