truncate

        # Float.truncate

(from ruby core)
---
    truncate(ndigits = 0) -> float or integer

---

Returns `self` truncated (toward zero) to a precision of `ndigits`
decimal digits.

When `ndigits` is positive, returns a float with `ndigits` digits after
the decimal point (as available):

    f = 12345.6789
    f.truncate(1) # => 12345.6
    f.truncate(3) # => 12345.678
    f = -12345.6789
    f.truncate(1) # => -12345.6
    f.truncate(3) # => -12345.678

When `ndigits` is negative, returns an integer with at least
`ndigits.abs` trailing zeros:

    f = 12345.6789
    f.truncate(0)  # => 12345
    f.truncate(-3) # => 12000
    f = -12345.6789
    f.truncate(0)  # => -12345
    f.truncate(-3) # => -12000

Note that the limited precision of floating-point arithmetic may lead to
surprising results:

    (0.3 / 0.1).truncate  #=> 2 (!)

Related: Float#round.