Why is rounding important when dividing a decimal by a whole number

Rounding is important, because you could have endless quotients.
For example, 10 / 3.3 = 3.3333333333333333333333333333333333333.

It is recommended that you stop at the hundreths place and round.

Rounding is important when you are dividing decimals because sometimes you can get a number that just keeps repeating so in that situation it would be better to estimate