What are decimals?

Decimals are a way to express a piece of a whole thing. Fractions do the same thing - it's really all about what is the convenient form to use when talking about numbers between 0 and 1.

Explanation:

Decimals are a way to express a piece of a whole thing. Fractions do the same thing - it's really all about what is the convenient form to use when talking about numbers between 0 and 1.

Consider a pizza. If I slice it in 2 and take 1 piece of it, I have $\frac{1}{2}$. If that piece is too big to stuff into my mouth all at once and I cut it in half again, I'll end up with $\frac{1}{2} \times \left(\frac{1}{2}\right) = \frac{1}{4}$ pieces. It's easy to operate with fractions this way.

If I did the same thing with decimals, I'd start with $0.5$ of the pizza. And then in cutting the pizza piece in half again, I'd have to multiply $0.5 \times 0.5 = 0.25$ - this is already starting to get clumsy!

In another situation, let's say I have a situation where the fractions are getting complicated - maybe there are 1,347 acres of farmland in a town and an owner owns 437 of them. If I wanted to write this in fractional form, I'd have:

$\frac{347}{1347}$, which is big and clumsy and hard to understand just how big it is. But I can simplify what I'm looking at by converting to decimal form and rounding:

347/1347=0.25760950259~~0.26=26% It's easier to see that the one owner owns about 26% of the farmland in the town. And perhaps to make it even easier to see, we can round again to the closest quarter and therefore it's close to 0.25=25%=1/4