This is one of those "too much time on your hands" things, but can be helpful sometimes.
In the various IT fields, you’ll often come across measurements in meters, and some of us Yanks would rather see feet.
Your first solution is to Google it, if you type "xyz meters to feet" Google will open it’s calculator at the top of the search results.
The second solution is a quick bit of head math that really isn’t too difficult, just a few rules apply. This calc can be off by as much as a half a foot high or low, it it only supposed to get you close, not perfect!
Firstly, 1 meter = 3.28084 feet.
Rule 1: Multiple the meters by three.
Rule 2: Add one quarter of your original meters onto the product. Because it’s .28, we are rounding down to the easier .25. We do have to account for the missing .03 though, that’s rule 4.
Rule 3: If you cannot divide evenly by four, just add another 1 if there is a remainder. For example take 19. 19 * 3 = 57. A quarter of 19 is 4 with remainder 3, just add one more because of the high remainder. So 57 + 4 + 1 = 62. The real number is 62.336. Works for me. Sometimes this does work if the remainder is small. Take 17 as an example. 4 goes in to 17 with remainder 1, but if I add another 1, I go over. 17 * 3 + 4 + 1 = 56, real number 55.7743. So we are close in a round-up sort of way, but if you’d rather round down, don’t add the extra 1 for a remainder of just 1. In fact, if you want to always be rounded down OR UP for safety’s sake, add or don’t add this remainder as needed.
Let’s see some examples before we move on to rule 4.
If you see 12 meters, you first multiple by 3 to get 36. Then you quickly estimate a quarter of 12, which happens to be 3, and add 3 on to 36, making 39. Thus 12 meters is roughly 39 feet. In fact it’s 39.3701.
If you see 15 meters, that is 15 * 3 + 3 + 1 = 49. Real answer 49.2126.
Rule 4: The last rule is this, at about 33 meters, the unaccounted for .03 adds up to 1. Remember, 1 meter is 3.28084 and we are rounding to one quarter which is .25. That missing .03 is adding up. If we take 1 / .03 we get 33.33333. In other words, at about 33 or 34 meters we’ll need to account for and extra 1 foot.
When calculating 33, 34, and 35, we have a remainder and thus are adding 1 already and this works, but at 36, we can divide evenly again by 9. 36 * 3 + 9 = 117, but the real number is actually 118.11. This is because we’ve left out too many .03s and they have now added up to an extra 1 foot. The basic fourth rule is, at about every interval of 33, throw one more on there to catch up unless there is a remainder. If you have a remainder and are already adding 1, that is one less to add with this rule.
The full calc is something like this: "Take meter times 3 plus meter divided by 4. If remainder then +1 (or don’t add if remainder is only 1). For every multiple of 33, +1 again except when adding 1 for remainder."
That sounds convoluted! It’s really not that hard, these rules are only to get a guestimate of the real number to within half a foot or so, it works pretty well actually. Let’s see a big number in action with rule 4:
Take 100 meters. That is 100 * 3 + 25 + 3 = 328. The extra 3 are because we’re roughly in the third multiple of 33. The real number is 328.084. That was a good guess!
However, if we had 101 meters, there will be a remainder, so instead of adding 3 and another 1 for the remainder, we’ll let the remainder cancel out one of the rule 4 additions thus we will still add just 3 instead of 4. 101 * 3 + 25 + 3 = 331. The real number is 331.365.
The next highest number that we have an even division by four is 104. This would be 104 * 3 + 26 + 3 = 341. Real answer 341.207.
There you have it. Play around with the concept and you’ll see it’s not too hard to multiple by three, find a quarter of your original number, and throw a quick extra 1 or 2 or 3 in there depending on remainder or multiples of 33, you’ll get the hang of it and can rely less on Google. Then again, if you are a math genius, you’d just multiple the meter by 3.28084 and be done with it. The rest of us are stuck with this.