Since a decimal is an abbreviation for a fraction whose denominator is a power of 10, we already know how to do this. We don't even have to dig deep to recall the process. We can dig pretty shallow.
Start with a decimal, for example: 0.456. The number to the right of the decimal point is the numerator of the fraction:
The denominator is the power of 10 with as many zeros as there were decimal places:
Finally, simplify the fraction to tidy things up:
Now, you have a choice when it comes to expressing yourself. You can either say you played video games for 0.456 of the day, or that you played video games for 57/125 of the day. Either way... how about you go outside and toss a football around for a bit? It's such a nice day.