Posted by Joe on .
If M=(1*2*3*4*......*1000) + 1, is M prime? I said no because 24001 can only be divided by 1 and itself, but I got a point off. Why is this?

Math 
Reiny,
probably since
1*2*3*4*...*1000 ≠ 24001
(just multiplying the last 3 numbers, 1000*999*998 is already 997002000, and we still have to multiply that by 997 other numbers.)
on the other hand, M is prime.
(I tried to figure out how you got 24000, and just realized that you simply multiplied 1*2*3*4*1000.
Did you not know what the .... in between the numbers meant ???) 
Math 
Frank,
Oh i did 1 times 2 times 3 times 4=24, then times the 1000 which is equal to 24000, then on the outside of thefraction it says add 1 so that's how i got 24,001. I don't know what the ...means that's how the problem was written. How does that make it prime though if you don't know the actual number?