Precision:

Computers cannot store arbitrarily long numbers.

Instead, floating point numbers are kept in two parts:

• the mantissa - 6 or more digits
• the exponent - the power of ten (or two)
• float, double, long double

example:

6.022 x 10 to the 23th (avogadro's number)

or .6022 x 10 to the 25th (normalized)

4 digits of precision

exponent:25

mantissa: 6022

with 6 digits precision, 1.000001 and 1.000000 are the same thing!