Because sometimes one form is easier to work with whereas at other times another form is.
Chat with our AI personalities
Before you can do that, you need to write each mixed number as an improper fraction, and then write both fractions with a common denominator. The only other choice is to write both mixed numbers as decimals, and then add them.
You would need infinitely many digits to write all numbers. However, to write all whole number (integers) you would need 4243.
To save writing out very large numbers or very small numbers that have lots and lots of noughts.
.2 You don't need to include the zero unless there are numbers after it in a decimal.
Adding decimal same as adding whole numbers