Multiplying 3 numbers at once to find age in seconds at 21 years

My calculator says that it has 12 digits memory, but only ten show. Is there a way to reveal these extra digits?

Last updated: around 2003
Level 3 update on Oct 27, 2008 (notes about Windows calculator and Excel)

Type:              Trick
Reliability:        - High
Ease of learning:   - Easy
Time saving:        - Doesn't apply
Usefulness:         - Completely useless
Difficulty:         - Easy
Overall:            - Good

1 How to use the trick

In fact, yes. Those extra digits are to help provide sufficient accuracy and to allow for rounding.

Try this, type the following into your basic calculator:

7 ÷ 65536

Your calculator may only show 0.0001068 as your answer. Scientific calculators would carry this out to (assuming it is a 12-digit (display, not memory)): 0.00010681152. Did you know that the calculator stores extra memory for the answer [definitely true with Windows calculator [calc.exe in the run menu]]? How do you get that memorized digit area to be displayed. Well, here's the trick. Take your answer and multiply by ten million to get 1068.11523438. Then subtract the first numbers before the decimal point, which, in this case, is 1068, and what do you get? It may reveal the hidden digit showing 0.115234375 as the answer. There you have it, all the digits to the answer.

2 Using Windows calculator

The windows calculator can do literally, thousands of digits (or so it seems). Windows calculator is special due to the fact that floating point precision doesn't actually allow for a lot of extra digits. It still works, but those beyond two extras is useless and randomized due to the nature of floating point calculations. At the time I wrote this (around 2002 or 2003), I wasn't into programming at all, but now that I am, I have more knowledge. Windows Calculator uses a 128-bit floating point variable, which allows for 32 significant figures for precision. This also works with Excel, but it only goes to 15 significant figures (a 64-bit double). This is still useful for getting random numbers though. Here's the square root of 10 to the first 250 digits using Windows calculator. If you were to search the actual value, it starts deviating from the actual after 32 or so digits. Do this:

Type or click the number "10" then click the "x^y" key and then type ".5" to give the square root of ten. [note you must have it in scientific view from the view menu]. Then, copy those digits to a different program like notepad. Without the trick, the calculator displays: 3.16227766016837933199889354443272. However, all you need to do is multiply by 1 and a number of zeros you feel comfortable with such as 4 to remembering the four digits that are added. In the long range, the square root of 10 would give:

3.162277660168379331998893544432718533689418694456143353335123428303084206384243441791019934473244664648633547293316685745186145807513439092617705201487338246448563328184862577123648414765926026213899282963235083211082152387744428553926563139842143580...

I could go on but it's senseless as it's just random numbers! Just as a tip, avoid the last digit as it might be rounded. If it is, then you'll have to delete it if you added it in. Of course, you don't need to be that precise, 5 significant figures is often more than sufficient for almost any occasion. Try it with the square root of 2 [by clicking 2 then the "x^y" key then using .5 as the value and enter. It should start with 1.4142135....

Footnotes:
* This trick is of minimal use. Such great accuracy is not needed, 5 sufficent digits is more than enough [that is, numbers like 589.36, 92,925,000, etc.]. Usually, 4 significant digits is enough.

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