the_time(): numeric result?

Hi!
I’m quite new to wordpress/php/css…

I need to get the date (day) of the post and do this (simple) mathematical expression:

– ((day -1) * 64)

The problem is that the string i’ve written seems wrong…

this is the code:
-<?php $echo ((the_time(‘j’) – 1) * 64); ?>px;”>

but this is what i get in theresulting html:
date of the post: 27
result in html: -27-64

date of the post: 24
result in html: -24-64

date of the post: 31
result in html: -31-64

i’ve tried several times, but it always seem that the output of the_time() is considered as a text string and not as a number.

What can I do? Wich is the right php string?

Sorry for my poor English and.. thank u for your help!
g10r3