Occurrence 499

Here is a worksheet to use with your children. It is very important that they understand how to write the number twenty seven. 

I found this through the Google Image Search. I am pretty certain it came from a scholastic website. 

occurrence 396

Marin Mersenne was a mathematician.  He is mostly known for the Mersenne Primes, but also for the Double Mersenne Primes, which have several 27's.

He also wrote twenty-seven books on the Geometry of Pierre de la Ramé.

He studied the mathematics of music and invented (I think) the twenty-seven key organ.

Here is another mention of the structure of an organ from a book.

occurrence 293

Mathematician Vaughan (1977) showed that all integers are the sum of at most 27 prime numbers.