In agile circles I have seen this exercise:

Have two people sit next to each other, each with a blank piece of paper and a pen.

Have them both simultaneously write down the numbers from 1 to 1: one time in decimal, one time in roman numbers and one time as letters of the alphabet (a=1, b=2...)

One person goes about it system by system (first decimal, then Roman... ). The other goes about it number by number (1,I,A,2,II,B...)

Time them both and compare their times.