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JavaScript uses a fixed number of bits, 64 of them, to store a single number value. There are only so many patterns you can make with 64 bits, which means that the number of different numbers that can be represented is limited. With N decimal digits, you can represent 10^N numbers. Similarly, given 64 binary digits, you can represent 2^64 different numbers, which is about 18 quintillion (an 18 with 18 zeros after it).

Jeffrrey Dominguez
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    Does this answer your question? [Number of bits in Javascript numbers](https://stackoverflow.com/questions/2802957/number-of-bits-in-javascript-numbers) – Peter B Sep 14 '21 at 22:49
  • Specifically, the largest non-big integer is `Number.MAX_SAFE_INTEGER`; the largest floating point value `Number.MAX_VALUE`. – Amadan Sep 14 '21 at 23:04

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Javascript traditionally stores numbers as a 64 bit floating point with a 52 bit mantissa an 11 bit exponent and the sign is 1 bit. Effectively this means that

Integers are accurate up to 15 digits. -- w3schools.com

Now with ES6 the BigInt proposal has been finalized, so you can access a second type of number when dealing with integers that may be larger than 52 bits. There also exist some libraries for operations on large numbers provided as strings.

That Realty Programmer Guy
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    Prefer linking to [MDN](https://developer.mozilla.org/en-US/) documentation for javascript references. see: [Why not w3schools.com?](https://meta.stackoverflow.com/questions/280478/why-not-w3schools-com). Relevant to your answer: [BigInt](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/BigInt), [Number](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number), [Number.MAX_SAFE_INTEGER](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number/MAX_SAFE_INTEGER) – pilchard Sep 14 '21 at 23:19
  • @pilchard in this instance, I've linked to both. w3schools actually had a cleaner summary than MDN. Plus its "datedness" is desirable here – That Realty Programmer Guy Sep 15 '21 at 06:31