In middle school, solving unit rate begins with rates involving whole numbers. This sometimes leads to fractional unit rates, but not always (as shown in examples [katex] 1\ ext{-}3 [/katex] on this page). Then the topic progresses to include rates with rational numbers, including rates with the original number of units as decimals, integers and fractions. Working with these rates requires solving rational operations to calculate the unit rate (as shown in examples [katex] 4\ ext{-}8 [/katex] on this page).