A factor is a number that divides a number. The number 6 is a factor of 12 since 6 divides 12. It is easy to see that 1, 2, 3, 4, and 12 are also factors of 12. Looking at the numbers in the tables below, we can see that some numbers have only 2 factors, […]

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# Elementary School Number Theory

## The Geometry of the Least Common Denominator

In mathematics, in putting together things, we must have a commonality; we must add objects that belong to the same set. We add 2 apples and 4 apples to get 6 apples. We do not add apples and oranges and come up with a single- kind-of-fruit-sum. This is also true with numbers and measurements: we add, […]

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## Making Sense of Exponential Growth

Money on Chess Squares A chessboard has 64 squares. If we are going to place 1 cent in the first square, 2 cents in the second square, 4 cents in the third square, and so on, how much money do we need to fill all the 64 squares? From the pattern above, it is clear that the […]

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