Factorials and Order of OperationsDate: 09/21/2000 at 22:13:18 From: Kiaran D Subject: Factorials, powers,and Order of Operations Where do factorials go in the Order of Operations? I've been thinking that factorials would go with exponents, but on the other hand, factorials go with multiplication. Date: 09/21/2000 at 22:53:25 From: Doctor Peterson Subject: Re: Factorials, powers,and Order of Operations Hi, Kiaran. Good question! I would put factorials with functions, something you don't often see listed in the order of operations. If you are not familiar with functions, you can think of them very simply as something to be done to a single number (or sometimes a list of numbers) that produces a number as a result. The square root and the trigonometric functions (sine, cosine) are examples of this. Technically, the factorial is called a (postfix) unary operator, which means essentially the same thing. Because these don't stand between two numbers, but only relate to one number, they are thought of as being attached directly to that number; if you want to apply a function or unary operator to a whole expression, you have to use parentheses. That puts functions at the top of the order of operations, just after parentheses. For example, this means that the factorial applies only to the 5: 3 + 4*5! = 3 + 4*120 = 3 + 480 = 483 while this applies it to (3 + 4*5): (3 + 4*5)! - Doctor Peterson, The Math Forum http://mathforum.org/dr.math/ |
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