7.5 * 2 results in 15., with a trailing dot. How can I get rid of it?

Using zsh: - width=7.25; echo $(( width * 2 )): the output is 14.5 - width=7.5; echo $(( width * 2 )): the output is 15., with a trailing dot This seems to be a very basic thing, but I haven't figured it out. How can I get just 15, without the trailing dot, in the second example?