Creating transparent text within an object?

Hi everyone,

I have a quick question. I have been trying to figure out how to create text within another object that blends in with the background (behind that object).

Here is an example (from shirt site ugmonk.com): http://cache0.bigcartel.com/product_images/871887/math_new2.jpg

If you notice the "two plus three equals" portion on the top left of the 5 blends in with the color of the shirt (so if the shirt was red or blue, the "two plus three equals" would show up as red or blue instead of yellow). How do you do this in photoshop? I've been trying to find a tutorial on this for a while, but to no avail. Any help would be appreciated. Thanks!

Use the text mask tool to cut out the area you want. Then any layer beneath will show through.

wow thank you so much! i appreciate it

Just wondering: is there any way to do this type of effect, but not with text? such as a brush?