When dividing 22 into 121 , you are cosidering how many times 22 goes into 121. This is called division.
Now how do we use division to find this?
well we do 22 over 121 or 22/121
The next step is the conversion to decimal.
How do we figure this out? well we use multiplication through the remainder theorem. The way this works is we figure out how many times 121 goes into a quantity of another number so,
121 goes into 22 how many times. Well 0, thus by the reaminder theorem we will add a zero assuming that we put a decimal place so now we know the number is atleast .XX
Now we have 220, so how many times does 121 go into 220? Well 1. We can add that to our number .1XX and we subtract that from 220 and then add a zero.
220-121 is 99 plus add a zero so we now have 990. 121 goes into 990 how many times? 8 times so we know the number is .18
This process could be continued forever, but there is no need. I hope I explained this well. Explaining core concepts like this generally should be done in person with someone.