### Brain Teasers

# 1-2-6-24

Series
Series teasers are where you try to complete the sequence of a series of letters, numbers or objects.Series

Finish this series:

1-2-6-24-120-??

1-2-6-24-120-??

### Hint

6!### Answer

7201! = 1

2! = 2

3! = 6

and so on

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### Solve a Puzzle

## Comments

Too easy. I solved it in, like, 5 seconds.

What doees an exclamation mark after a number mean? Please tell me!

The exclamation point indicates "factorial" -

the product of all the integers from 1 up to the number itself.

So 2!=1x2, 3!=1x2x3x4, 4!=1x2x3x4, etc.

the product of all the integers from 1 up to the number itself.

So 2!=1x2, 3!=1x2x3x4, 4!=1x2x3x4, etc.

That should read 3!=1x2x3. Not sure how the typo got in there.

Curiously 0!=1. Can you please explain that one.

0!=1 because of convention. It makes

a number of formulas involving factorials

work out without having to treat 0

as a special case. For example, the

number of ways you can choose k different

objects out of a set of n objects is

n!/((n-k)! * k!). If 0! wasn't 1, then

you would have to treat k=n as a special

case not covered by the formula.

a number of formulas involving factorials

work out without having to treat 0

as a special case. For example, the

number of ways you can choose k different

objects out of a set of n objects is

n!/((n-k)! * k!). If 0! wasn't 1, then

you would have to treat k=n as a special

case not covered by the formula.

this was a good teaser, tho i must admit, as long as you kno that ! is factorial, the hint is basically the answer. i dunno if thats good or bad...LoL

a clearer explaination in the answer would help

but once I got it, it was good

but once I got it, it was good

It started out hard, but the hint helped. Wonderful!

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