On the next web exercise (finding the average of two signed numbers), you will need to report your answers in decimal form.

All your answers will initially be fractions with a denominator of $\,2\,,$ and you should be able to convert them to a decimal without having to pull out your calculator!

To convert (say) $\,\frac{15}{2}\,$ to decimal form, go through this thought process:  How many times does $\,2\,$ go into $\,15\,$?

Answer:   It goes in $\,7\,$ times, with $\,1\,$ left over. The answer is $\,7.5\,.$

Here are the details: $$ \begin{align} \cssId{s12}{\frac{15}2} &\cssId{s13}{\ =\ \frac{14+1}2 } \cssId{s14}{\ =\ \frac{14}2 + \frac12}\\ &\cssId{s15}{\ =\ 7 + \frac 12 } \cssId{s16}{\ =\ 7 + 0.5}\\ &\cssId{s17}{\ =\ 7.5} \end{align} $$

To convert a negative fraction (say, $\,-\frac{19}{2}$) to decimal form, go through this thought process:  Firstly, the answer will be negative. How many times does $\,2\,$ go into $\,19\,$?

Answer:   It goes in $\,9\,$ times, with $\,1\,$ left over. The answer is $\,-9.5\,.$

Of course, if $\,2\,$ goes in evenly, then you don’t need a decimal at all to report your answer. For example, $\,-\frac{16}2 = -8\,.$

Practice