Because! The numbers are an everyday needed item, and knowing them in Finnish will help you a lot!
NUMEROT (NUMBERS)
To make numbers between 10 to 20, use numbers 1 to 9 and add "toista", which means 2nd. It's the 2nd coming of these numbers so that is the reason why it's there.11 = yksi + toista = yksitoista
15 = viisi + toista = viisitoista
17 = seitsemän + toista = seitsemäntoista
Higher numbers you might want to know are:
A lot of stuff in Finnish is written together. To make numbers between 20 – 30, 30 – 40 and so on, just add the number after it. This applies to number 100 as well.