Metric Day the easy way

Today is the 10th of October. As with previous years, I choose to recognize today as "Metric Day". I last wrote an article about Metric Day in 2011 and, in the time since then, I've noticed that many people in the United States of America are becoming more comfortable with the International System of Units (SI) [Wikipedia]. I'm not suggesting that those individuals are comfortable with its use, but it certainly seems that a growing number of people are recognizing the convenience of it in our global community. (Similar to the change I have witnessed in the public opinion of Daylight Saving Time.)

The use of SI is wide-spread and those who are unfamiliar with SI find themselves somewhat isolated in a growing global community. Today, I hope to provide some easy-to-remember tips to those individuals who are curious about SI, but are reluctant to adopt its use.

Conversationally, we often discuss the environment and our own comfort within it. As a result, common units of temperature are often cited and discussed. Rather than wrestle with a more accurate mental conversion or calculating one using a computer, try to remember the tips below; it might speed your conversational comprehension and free up your mind for the social aspect of agreeing that 30°C is rather warm.

F minus 30, divided by 2 ≈ C
C multiplied by 2, add 30 ≈ F
People find themselves discussing distances internationally for a variety of reasons. Perhaps you or someone you know is in the US military and stationed abroad. Or maybe you have a friend interested in joining you on a 5 kilometer run, but they hesitate because they're only comfortable running 3 miles. I hope the quick methods below will help you or your friend adjust quickly to the measurement most familiar.

mi divided by 5, multiplied by 8 ≈ km
km divided by 8, multiplied by 5 ≈ mi
mi divided by 3, multiplied by 5 ≈ km
km divided by 5, multiplied by 3 ≈ mi
(This second set of distance conversions might be noticeably less accurate for numbers higher than 10)
Technology has allowed our ever-growing population to become evermore connected. Borders and boundaries begin to fade in meaning as we correspond and collaborate with people instantaneously, regardless of our location or theirs in world. In a world of dizzying communication, using the same measurement "language" is the difference between clarity and confusion.