Everyday Heuristics

When navigating through life you will often come across some unit translations. A common occurrence for an American might be converting the temperature in Celsius to Fahrenheit. In this post I have consolidated some of my favorite heuristics for quick, approximate calculations.

Temperature

The exact equation for converting Celsius to Fahrenheit is $$ F = (9 / 5 * C) + 32 $$

This can be quickly approximated by the heuristic “double and add 30”, which is far easier to do in your head.

Distance

1 yard is technically 0.9144 meters, but that is close enough to generally be equal to 1.

5 kilometers is just above 3 miles, while 1 mile is just above 1.5 kilometers.

Area

Soccer fields vary in size, making any reference prone to error. However the pitch size recommended by FIFA is 105 meters by 68 meters, for a total area of 7,140 square meters. Given that an acre is defined as 4,047 square meters, we can determine: $$ (105m * 68m) / 4,047m^2 = 7,140m^2 / 4,047m^2 \approx 1.764 $$ Or in other words, 1 acre is a little more than half a soccer field.

Money

Given a 40 hour work-week and 52 weeks in a year, the average full-time worker has a little over 2000 hours worked per year. This makes it simple to convert an hourly rate to annual or vice versa. If you know your hourly rate, simply double it and add three 0’s and that is your annual income.