Many designers think they are bad at math. Thankfully, InDesign is good at math.
Input fields in InDesign can do simple math. For example:
Addition, subtraction, multiplication and division. Have a box that is 4.25 inches wide and you want it to be 1 inch wider? Just type "+1" after the curent measurement. Need to resize a box to 1/3 the current width. Type "/3" behind the measurement in the width field.
Conversions. InDesign will also convert measurements for you. If your document is set up for picas and you need to input a measurement in something other than picas, just type the measurement AND the unit of measure (for example, "7 in" or "3 mm") and InDesign will convert it to picas. This works for lots of different units -- inches, millimeters, centimeters, points and more. You can even do addition or subtraction between numbers with different units of measure and InDesign will figure it out for you. For example, typing "7 in + 3 pts" will yield 7.0417 inches.
Enjoy. I'm sure this is a reminder for many of you, but I run across people everyday that don't know that InDesign can do simple math. I typically use unit conversion and division a lot in InDesign. As a bonus, most Adobe apps have fields that can do math – not just InDesign. I use it in Illustrator all the time.
Every Wednesday, I post a quick tip for an Adobe app.