Values of this type represent real numbers, with the usual limitations of IEEE-754 floating point type: it cannot represent very large or very small numbers, and the precision is limited to only about 15 digits. For complete details on the IEEE-754 standard and its limitations, see the Wikipedia article.

A floating-point constant may be preceded by a
“`+`

” or “`-`

” sign, followed by a string of one or
more digits containing a decimal point (“`.`

”).

For very large or small numbers, you may express the
number in exponential notation by appending a letter
“`e`

” followed by a power of
ten (which may be preceded by a sign).

For example, Avogadro's Number gives the number of atoms
of carbon in 12 grams of carbon^{12}, and is written as
6.0221418×10^{23}. In
Python that would be “`6.0221418e23`

”.

Please note that calculations involving `float`

type are approximations. In calculator
mode, Python will display the numbers to their full
precision, so you may see a number that is very close to
what you expect, but not exact.

>>> 1.0/7.0 0.14285714285714285 >>> -2*-4.2e37 8.4000000000000004e+37