These are exact for representing fraction. They are stored as two integers, a numerator and denominator. They need to be converted to Float in order to be readable. They’re a bit slower than floats. Use them only when there is a need to do calculations with exactness. There’s several notations.

All of these are equivalent:

1.1r
1.1.to_r
Rational('1.1')
Rational(11, 10)

This is not in the core library but in the standard library, so it needs to be required.

There are exact for representing fractions as well (some exceptions). Inspection uses scientific notation. Unless instantiating using strings or integers, the precision argument needs to be provided. This is useful for dealing with fixed precision numbers (like money). Apparently, this is the slowest of all the numeric types, so use it when it’s necessary.

require 'bigdecimal'

BigDecimal(1.1, 2)

1.1