Finding the square<span> root of a </span>number<span> is the inverse operation of squaring that </span>number<span>. Remember, the </span>square<span> of a </span>number<span> is that </span>number<span> times itself. The perfect squares are the squares of the whole </span>numbers<span>. The </span>square<span> root of a </span>number<span>, n, written below is the </span>number<span> that gives n when multiplied by itself.
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Answer:
3
Step-by-step explanation:

And,
$ \sum (2i+1)= \sum (2i)+ \sum_{i=1} ^{4} (1) $
$=\sum_{i=1} ^{4}(2i) + 1+1+1+1 $
$=\boxed{\Big(\sum_{n=1} ^{4}(2n)\Big) +4}.... \text{Variable in Summation doesn't matter}$
Hence the difference is 3.