The parseInt function made my number loose precision: the last two digits changed from 18 to 20:
console.log(parseInt('76561198236425518', 10));
76561198236425520
Why did that happen and how to fix it?
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Aracthor
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Misha Kogan
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I am update my question – Misha Kogan Sep 25 '15 at 07:13
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1JavaScript double floating point variables only have `2^53` bits of precision. The number in your example is roughly `2^56`. – Tim Biegeleisen Sep 25 '15 at 07:16
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I think that it isn´t necessary put the radix if you want use decimal system (10) – Eloy Fernández Franco Sep 25 '15 at 07:18
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Thanks a lot, can i use something to convert string to number? But don't use parseInt? – Misha Kogan Sep 25 '15 at 07:19
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Numbers are stored as floating point with a 53-bit manttissa. This limits the precision you can have to less than what you have in that number of yours, hence it has to round to the nearest floating point number it can represent.
The actual number of bits needed to represent a number N can be calculated as about log2N or, if you're working on a calculator that can't calculate logarithms to base two, logxN/logx2.
The value of log276561198236425518, roughly 56.1, shows that it requires about 56 bits, which is why it's not exact near the end.
paxdiablo
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