# 100 Million Digit Prefactor Project

The **100 Million Digit Prefactor Project** (or just **100MDPP**) is a project, which factors Mersenne exponents to prepare for an eventual search for the first 100 million digit prime for which there is a prize of **$150,000**.

## How to participate

You can use Prime95, mfaktc / mfakto, or Factor5. Instructions on how to use Prime95 for this can be found here: LMH how to on Mersenneforum.org. mfaktc/mfakto can be used in a similar manner to Prime95 (it can read the Prime95 worktodo.txt file and the results can be submitted via the manual assignment pages.) mfaktc/mfakto is very fast and can be used to take exponents to a bit level higher than practical by using Prime95 alone. Factor5 can be found at: Factor5 home page. Use of Factor5 is **now discouraged**, as Prime95 and PrimeNet can now handle expos and assignments in this range and Prime95 is faster.

Currently (early 2011), those using mfaktc/mfakto are encouraged to take exponents that are already at or above the 74 bit level; and to take them to 78 bits or higher. Those using Prime95 are working to raise exponents to 74 bits. The area where most of the work is being done is between 332,192,831 and 332,399,999. Individuals with slower processors and farms are encouraged to work in the area between 332,399,999 and 332,599,999.

## Status

The project is currently running! Go to the 100MDPP thread on the Mersenneforum to see the current status.

## History

The project started with the introduction of 'Factor' by Luigi Morelli. It was handled using a Geocities website and e-mail. After an initial rush of enthusiasm, Uncwilly let the project slide into decline. The hand management of the exponents and the drop in involvement of fellow helpers caused this first flush to fade.

Later, OmbooHankvald picked up the running, then handed it to gribozavr (Dmitri Gribenko).

Once, a >10 million digit Mersenne prime was discovered, interest in working on **100** million digit primes picked up sharply. This coupled with new versions of Prime95 and PrimeNet, allowing for automatic exponent tracking, breathed new life into the project.

Uncwilly has resumed a leadership role in prefactoring numbers in this range. Many other users are now signed up to LL test exponents, this causes them to trial factoring to finish any remaining factoring (to the 77 bit level.) This has had a large favorable impact on the project.

There is now available trial factoring software for GPU's. Because of the many cores, GPUs are much faster. Several users are now using mfaktc/mfakto to take exponents beyond the 77 bit level. Many have been taken to 79 or 80. The total throughput on this project has seen a dramatic rise since the addition of GPUs.