In addition to being a great place to store all of your notes and other content, OneNote also serves as a calculator. For example, say you're taking some notes and you suddenly have to do some quick arithmetic. You can either try to uncover those dusty memories of how to do fundamental mathematics in the far-reaching, (and in my case, dark), corners of your brain…or, just let OneNote's Napkin Math feature figure out the result for you.

Here's how it works. Just type the equation anywhere on OneNote's page surface, followed by an equals sign "=" and as soon as you press the <Spacebar> or <Enter>, OneNote performs the calculation.  For example, let's say you want to calculate the average monthly sales of bolts that sell 70 thousand per year: just type "70,000 / 12 =". Once you press the <Spacebar> OneNote does the following: "70,000 / 12 = 5,833.3333".

Or perhaps your in a meeting discussing the purchase of 18 new company vehicles for your sales force at $29,000 a car.  Just enter "18 * $29,000 =". OneNote resolves to "18 * $29,000 = $522,000.00". Notice the automatic inclusion of the decimal point (.) in the result. That's because of the dollar sign ($).

If you want to figure out the monthly payment of a loan you're about to take out just use pmt(i; n; b), where i = interest rate, n = number of payments and b = the amount borrowed. So if you type the following equation: "pmt(.019; 36; $50,000) =" you'll get: "pmt(.019; 36; $50,000) = $1,930.28".

Maybe you just want to impress your fellow classmates by showing them how quickly you can work out the answers to those complicated calculations.  Tip: Just don't let them see your fingers typing away on the keyboard.

Whatever the reason, you're sure to benefit from OneNote's built-in calculator.

Here are some more examples of expressions that can be calculated in OneNote:

• You type: "sin(30) =". OneNote resolves to: "sin(30) = 0.5"
• You type: "(6 + 7) / (4 * sqrt(3)) =". OneNote resolves to: "(6 + 7) / (4 * sqrt(3)) =1.876388374866284"
• You type: "5 ^ 4 =". OneNote resolves to: "5 ^ 4 = 625"

See below for a list of supported operators and math/trig functions.

Tips:

• Use the percent sign (%) to make calculating percentages easier
  • Type: "35 * 20 % =", you get: "35 * 20 % = 7"

• Lower case x, upper case X and asterisk (*) are all valid multiplication operators
  • "2 x 3 X 5 *9 =" resolves to: "2 x 3 X 5 *9 = 270"

• You can use pi and phi as constants
  • "1 * pi=" resolves to: "1 * pi = 3.141592653589793"
  • "1 * phi=" resolves to: "1 * phi = 1.618033988749895"

• Factorial numbers are computed like so:
  • "5 ! =" resolves to: "5 ! = 120"

• Use 'mod' to calculate remainders
  • "38 mod 12 =" resolves to: "38 mod 12 = 2"

• To disable napkin math in OneNote, click Tools -> Options -> remove the checkmark from Calculate mathematical expressions automatically.
• Be sure the symbols you use in your equation are valid symbols. For example, try typing "#38 mod 12 =". You would probably expect a result of 2. However, because the hash mark "#" invalidates the number 38, OneNote is really solving the equation "12 =", for which the result is 12.
• Finally, here's a note from John Guin's blog on napkin math:

And here is the final part that surprised me the most. The Greek letters for pi and phi are supported as constants in both lower case and capital forms. Try it out:

π= should give 3.141592653589793

Π=should give 3.141592653589793

φ=should give 1.618033988749895

Φ=should give 1.618033988749895

(Use character map to insert the symbols if you want).

List of supported operators:

List of math and trigonometry functions: