Precision of Floating Point Numbers

Consider writing the value 1/3 in decimal notation:

0.333333333333333333

There is no limit to the number of 3's required for complete accuracy. With a limited amount of paper, you can not be completely accurate. With any data type, there is a limited number of bits. They cannot accurately represent an unlimited number of 3's.

The data type float has 23 bits of precision. This is equivalent to only about 7 decimal places. (The rest of the 32 bits are used for the sign and size of the number.)

The number of places of precision for float is the same no matter what the size of the number. Data type float can represent numbers as big as about 3.4E+38. But the precision of these large numbers will also be about 7 decimal digits.

Remember: data type float has about the range and precision of a cheap electronic calculator. This is usually not sufficient.