Truncate a floating point number without rounding up

Question

I have a floating point number that I want to truncate to 3 places but I don\'t want to round up.

For example, convert 1.0155555555555555 to 1.015

Answer 1

You can also convert to a BigDecimal, and call truncate on it.

1.237.to_d.truncate(2).to_f # will return 1.23

Answer 2

Since ruby 2.4 Float#truncate method takes as an optional argument a number of decimal digits:

1.0155555555555555.truncate(3)
# => 1.015

Answer 3

Assuming you have a float, try this:

(x * 1000).floor / 1000.0

Result:

1.015

See it working online: ideone