The answer depends on what you wish to do with decimals.
terminating decimals and repeating decimals
terminating decimals non terminating decimals repeating decimals non repeating decimals
Two of them are terminating decimals and recurring decimals
Terminating decimals are decimals that end, such as, 2.384. Non-terminating decimals that don't end, such as, 0.3333333333.......
6.7,6.8,6.4,5.9
You need decimals when you measure and fractions. You need decimals, because to measure and fractions. Also, so whole numbers could exist if there are decimals. There will be no math if there's no decimals.
3rd. Adding Decimals 5th - Adding and subtracting 6th - Dividing Decimals
Some decimals are. Counting numbers are a proper subset of decimals.
terminating decimals repeating decimals
Some decimals repeat. Some decimals go on forever. Some decimals stop. Those are called terminating decimals.
Yes providing you change the fractions into decimals or change the decimals into fractions
They are decimals that have equal value.