This is not a lens about using a calculator to find a square root. This is not a lens about finding a square root to its nearest 10th or 100th or 2 places. This is a lens that helps you get from a large number's square root to a smaller number's square root.
In other words, this will show you how to go from ([square root] 20) to (2 ([square root] 5).
Reducing Irrational Square Roots
One of the sorts of problems that shows up on Algebra tests is taking a square root of a number that isn't a perfect square (see a list of all the integers that are perfect squares from 1-625 at the bottom of this lens) and reducing it to an easier to handle version. For example, in the picture here, we start with [square root] 98. But, if you notice when you look at the list, 98 is NOT a perfect square.
98, however, equals 2 X 49. 49 <b>is</b> a perfect square -- it's 7 squared (or 7 X 7). So, as you can see in the second step, [square root] 98 = [square root] 49 X [square root] 2. Or, more succinctly, 7 X [square root] 2.
If the number you are trying to divide is one you don't know (as in you can't tell right away by looking at it what perfect square might be a factor), check out <a href="http://www.squidoo.com/LowCommonDenom">Lowest Common Denominator</a> to see how to break numbers into their factors. Or, if the number is low enough, you can look at the list of squares from 1-625 further down in this lens and work from there.
This is a list of the first 25 positive integers with their squares.