Let the total number of kids in Mr. Levans' 3rd grade class be x.
We know that each kid in the class made a Valentine for every kid in the class, including himself or herself.
So, the first kid made x Valentines. Likewise, the second kid too made x Valentines. If we go on so on and so forth, we will note that even the last, or the
kid made x Valentines too. Thus, this way we know that every kid made x Valentines.
Therefore, the total number of Valentines made are
. It is given in the question that the number of Valentines made is 484.
Therefore, from the above information we conclude that:

To find x we will have to take the square root of both sides. Which will give us:


Thus, the number of kids in the class is 22.