Approximation error

Approximation error is when a calculation or measurement isn't perfect. That means, when you try and figure out something, you might not get the exact answer. Instead your answer is close, but not quite what it should be. For example, if you want to figure out how many jellybeans are in a jar, you could count them one-by-one but you might not get the exact right number. That's because there are too many to count so you have to approximate - or guess - how many there are. That means your answer might not be the exact right number, but it should be close.