Decimals in written form
We're asked to write this right here in word form, and I'm not saying it out loud because that would give the answer away. We have 63.15 that we want to write in word form. Well, the stuff to the left of the decimal point is pretty straightforward. Let me actually color code it. So we have 6, 3. Let me do it all in different colors. And then we have a decimal, and then we have a 1 and a 5. There's one common way of doing this, but we'll talk about the different ways you could express this as a word. But we know how to write this stuff to the left. This is pretty straightforward. This is just sixty-three. Let me write that down. So this is sixty-three. And instead of the decimal, we'll write, and. Now there's two ways to go here. We could say, and one tenth and five hundredths, or we could just say, look, this is fifteen hundredths. One tenth is ten hundredths. So one tenth and five hundredths is fifteen hundredths. So maybe I can write it like this: sixty-three and fifteen hundredths. Just like that. Now, it might have been a little bit more natural to say, how come I don't say one tenth and then five hundredths? And you could, but that would just make it a little bit harder for someone's brain to process it when you say it. So it could have been sixty-three-- so let me copy and paste that. It could be sixty-three and, and then you would write, one tenth for this digit right there, and five hundredths. Sixty-three and one tenth and five hundredths is hard for most people's brains to process. But if you say, fifteen hundredths, people get what you're saying. Not to beat a dead horse, but this right here, this is 1/10 right here and then this is 5/100, 5 over 100. But if you were to add these two, If you were to add 1/10 plus 5/100 -- so let's do that. If you were to add 1/10 plus 5/100, how would you do it? You need a common denominator. 100 is divisible by both 10 and 100, so multiply both the numerator and denominator of this character by 10. You get 10 on the top and 100 on the bottom. 1/10 is the same thing as 10 over 100. 10/100 plus 5/100 is equal to 15 over 100, so this piece right here is equal to 15/100. And that's why we say sixty-three and fifteen hundredths.