Don’t listen to all those people who tell you it’s better to pick up a new hobby, learn to play an instrument, take a course or do anything else with any intrinsic value with your spare time: unbeknownst to all of these “productive people,” there is a multitude of completely and utterly useless things you can learn to do instead. If you’ve ever thought, “I really, really want to be able to solve spot the difference puzzles faster than my friends” or “the one thing I really need in my life is a mastery of Morse code,” then you’re in luck. Never fear, intrepid learner of nonsense, your wishes are about to be fulfilled!
Estimate the time until sunset
Turn your hand on its side, so your fingers point across your body.
Line up your hand so that the top edge of your index finger lines up with the bottom of the Sun.
Count the number of finger widths between the bottom of the Sun and the horizon. Each finger width is equivalent to 15 minutes, so the four fingers on your hand represent one hour until sunset. The remaining time until sunset is simply (in minutes) the number of fingers between the Sun and the horizon multiplied by 15, or (in hours) the number of four-finger widths between them.
Learn Morse code
Use an image of the Morse code for different letters and numbers superimposed onto the characters themselves (see Resources) to memorise the code for each character.
Practice writing messages to get to grips with it, referring to the image whenever you need to.
Proceed to decode Morse code messages used in films or on TV (don’t worry if nobody seems impressed, they’re probably just jealous) and transmit messages to people they’ll never understand.
Play “Happy Birthday” on a touch-tone phone
Press “1,” “1,” “2,” “1” for “hap-py birth-day.” This repeats at the start of the first two lines of the song, ending with “6,” “3” the first time and “9,” “6” the second time for “to you.” Play the first two lines to practice.
Press “1,” “1” for the start of the third line (“hap-py”), followed by “#,” “9,” “6,” “3,” “2” (“birth-day, dear [name-here]”). The first four notes of the second part is just a straight line up from “#” to “3” on standard-layout phone keypads.
Finish with “9,” “6,” “9,” “3,” “6,” “3” (“hap-py birth-day to you”).
Solve “spot the difference” puzzles
Squint or cross your eyes so you can see two of each image. You can do this by trying to look at the right image with your left eye and vice-versa.
Adjust your vision with the aim of making the two central images overlap. Focus on the picture in the middle as much as you can. See Resources for an illustrated guide to this.
Blink and then refocus on the image in the middle. Eventually, it will fall into focus, with small parts of the central image flickering. The two images are superimposed on one another in the centre, and the flickering reveals the differences between them.
Convert between miles and km in your head
Add 60 percent to the amount in miles to get the amount in km. The best way to do this is to add 50 percent and 10 percent separately.
Choose a distance in miles to use, for example 80 miles. Divide by 2 to find 50 percent of this (40 in this example) and divide it by 10 to find 10 percent (8 in this example). Add the original number, the 50 percent and the 10 percent together to get the result in km (80 + 40 + 8 = 128 km). The actual figure will be slightly off (an accurate conversion gives 128.7 km), but it’s a good estimate. Admittedly, this skill is almost actually useful, but the fact you can just type "miles to km" into Google to find it out basically renders it useless.
Choose a distance in km to convert into miles. This method works in the same basic way but is slightly less accurate. Your aim is to subtract 40 percent from the km distance, which you do by subtracting 50 percent and adding 10 percent.
Divide your amount in km (90 km, for example) by 2 to find 50 percent (45) and divide it by 10 to find 10 percent (9). Subtract the 50 percent figure from the original distance (90 – 45 = 45) and then add the 10 percent for the result (45 + 9 = 54 miles). The actual answer is more like 56 miles, but this is a close estimate. Alternatively (for more accuracy), you can multiply the amount in km by 5 and divide the result by 8 (90 × 5 = 450, 450 / 8 = 56.25) but the mental maths is harder.