Question

I'm thinking of a number from 1 to 10. It's prime. Twice the number plus one is prime. Twice the number minus one is not prime. What's the number?

Answer 1

2

Answer 2

is 1 a prime or 3*2 + 1 = 7

Answer 3

5

Answer 4

umm no it doesn't work

Answer 5

2 does not work

Answer 6

is 1 a prime??

Answer 7

1 is not prime

Answer 8

no, the first prime is 2

Answer 9

2,3,5,7

Answer 10

the number is 3?

Answer 11

nope, that fails "twice the number minus one is not prime"

Answer 12

it's 5

Answer 13

i got it iknow it has to do something with numbers humm 69?

Answer 14

oh yeah 5

Answer 15

5*2+1=11 which is prime
5*2-1=9 which is not prime

Answer 16

ghass1978 was right

Answer 17

ding ding ding

Answer 18

hmm how could i fall to such a question ughhh

Answer 19

lols, im feel so stupid, got an easy question wrong xD

Answer 20

i feel*

Answer 21

{{2, 5, 3}, {3, 7, 5}, {5, 11, 9}, {7, 15, 13}}
5 only.