<p>then you look at the answer key and see which one fits, to do the problem manually plugging variables in it take me 1 min +, plug it in a calculator and finding the answer take less than 30 seconds.</p>
<p>I guess if the problem wants you to find the roots to the nearest hundredth, using a calculator is fine. If it has exact answers, I find it best not to use a calculator.</p>