What is is 13 and 15 bad?

If you're referring to the numbers 13 and 15 in terms of superstition or cultural beliefs, here's some information:

1. Number 13:

   • In many Western cultures, the number 13 is considered unlucky. This superstition is known as triskaidekaphobia.
   • The association of 13 with bad luck is thought to originate from various sources, including the Last Supper, where Judas Iscariot, the disciple who betrayed Jesus, was the 13th guest.
   • Many buildings and hotels skip the 13th floor or have no room number 13 to avoid the superstition.

2. Number 15:

   • The number 15 generally does not hold a negative connotation across cultures as strongly as the number 13.
   • In numerology, 15 is often seen as a number that carries positive attributes, such as harmony and balance.

Overall cultural context is important, as perceptions can vary greatly depending on the cultural lens through which numbers are viewed. If the numbers 13 and 15 are part of a different context you're curious about, please provide more details.