# 3 Years of Sundays.

This is a story of doggedness, of persistence, of how attempts at a task one may try before success. If you're a regular This American Life listener, you may have heard this story before.

In the middle of the 17th century, a monk and mathematician (Marin Mersenne) published a formula for discovering prime numbers. His formula found a 21 digit number - 147,573,952,589,676,412,927 - which became mathematically famous as a super-large prime number.

In 1903, Frank Nelson Cole started his presentation "On the Factorization of Large Numbers" to the American Mathematical Society. He wrote Mersenne's famous prime on the blackboard, and then worked through the long multiplication to demonstrate that it was divisible by a nine digit number (193,707,721) and a 12 digit number (761,838,257,287).

Here's the most compelling part of the story. In the early 1900s, how long did it take Cole to find these two numbers and prove that Mersenne's famous number was not a prime number?

Three years of Sundays. These three years of Sundays were probably spent solving the problem by trying every possible solution - dividing Mersenne's number, by one number and then the next number and then the next. Three years of Sundays is 156 Sundays. For 155 of them, Frank Nelson Cole failed.

This is the marvelous thing about science, and scientists. Scientists are the type of people will fail for 150 Sundays, and still keep trying.