To make up for this I will move onto numbers, which will be a little complicated than you think.
So, there are two number systems. There is the Native Korean and the Sino-Korean systems.
A little history will help understand why they have two numeral systems. Sino-Korean is the lettering that is influenced by the original Korean lettering called Hanja. Because Hanja is mostly influenced by Chinese characters, that's where the Native Korean comes in. It's adapted from English and other various languages.
Now that we understand why there's two systems, why can't we just use one?
I honestly have no idea. I searched the inter-webs for an answer that could have been posted, but to no avail. I will ask someone I know personally to get a better understanding. I *presume* it's because the Sino-Korean was passed down, and then the Native Korean was adapted. Don't hold me against that.
Now, the numbers!
I will show you the basic 1 - 10.
Remember Professor Oh? Sure you do! Here she is for the NATIVE KOREAN numeral system.
And here is she again for the SINO-KOREAN: