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# Is integer x prime? (1) x = | x | (2) x! = | x |

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Re: Is integer x prime? (1) x = | x | (2) x! = | x | [#permalink]
Statement 1: x can be equal to |x| only for non-negative integers, but it does tell if x is prime or not

Statement 2: x!=|x|

Above condition is true for x=1,2

1 is not a prime number while 2 is a prime number => statement 2 is not sufficient

Combining both:

both conditions are satisfied when x=1,2 (same as statement 2)

So E is the correct answer

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Re: Is integer x prime? (1) x = | x | (2) x! = | x | [#permalink]
what does x! mean? did not get the b condition
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Re: Is integer x prime? (1) x = | x | (2) x! = | x | [#permalink]
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shikha.lakhani wrote:
what does x! mean? did not get the b condition

Definition

The factorial of a non-negative integer $$n$$, denoted by $$n!$$, is the product of all positive integers less than or equal to $$n$$.

For example: $$4!=1*2*3*4=24$$.

Properties

• Factorial of a negative number is undefined.
• $$0!=1$$, zero factorial is defined to equal 1.
• $$n!=(n-1)!*n$$, valid for $$n\geq{1}$$.
Re: Is integer x prime? (1) x = | x | (2) x! = | x | [#permalink]
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