Investopedia contributors come from a range of backgrounds, and over 25 years there have been thousands of expert writers and editors who have contributed. Robert Kelly is managing director of XTS ...

Calculating how far a number has declined from one year to the next is pretty easy if you are only considering a one year period. You subtract the current year's number from last year's number, then ...

Scientific American presents Math Dude by Quick & Dirty Tips. Scientific American and Quick & Dirty Tips are both Macmillan companies. Long time math fans may remember our first foray into the world ...

Percentage Formula: Percentages are a fundamental concept in maths, used frequently in daily life. It represents parts of a whole as fractions of 100. They're symbolised by the "%" symbol.

Percentages are a way of expressing proportion. Proportion tells you how much of one thing there is in relation to the whole. 'Per cent' means ‘out of 100’ and a percentage is written as a number with ...

Understanding the profit you can make selling products is the first step in analyzing the potential of the market for those products. Profit margin can be expressed as a dollar figure or as a ...

How to calculate percentages is easier than you think. Quick, what’s 36% of 25? Or how about 250% of 20? Learn a quick and dirty tip to help you calculate all of those pesky percentages in your head.