In Exercises 81–85, use a calculator's factorial key to evaluate ...

Question

In Exercises 81–85, use a calculator's factorial key to evaluate each expression. 20!/(20−3)!

Accepted Answer

Welcome back. I am so glad you're here. We are given this expression. The numerator is 34 factorial divided by the denominator is parentheses 34 minus four and parentheses factorial. And we are asked to evaluate this. Well before we put it into the calculator we can simplify in the denominator if we want. So we can do the 34 minus four. So the numerator would still be 34 factorial divided by in the denominator 34 minus four's 30 still factorial. If you can put that right into your calculator, great. If your calculators like mine and doesn't have a factorial button you've got a couple of options. You could start typing the numerator 34 times times 32 all the way down to one divided by in the denominator 30 times 29 times 28 all the way down to one. But if your calculator is again like mine it might not be able to enter that many numbers before it just gives up and says no can't type anymore in there. So that strategy works great if you've got a small number like seven factorial divided by five factorial. But since that's not what we're dealing with in this case you've got another option among many but one I'm going to suggest is that you can just pull up Google calculator which does have a factorial button and you can type right in here. 34 factorial divided by 30 factorial and hit equal to evaluate and there's our answer 1,113,024. We look at our answer choices and this matches with answer choice C. Well done, we'll catch you on the next one.

In Exercises 81–85, use a calculator's factorial key to evaluate each expression. 20!/(20−3)!

Key Concepts

Factorial

Permutations

Calculator Functions

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