Finding large primes.

Density Of Primes

The **prime distribution function** (n) specifies number of
primes n.

**Theorem 31.37**

For example, 48,254,942.

The probability that randomly-chosen n is prime
.
Thus, try
odd numbers near n to find a prime with high
probability.

For example, 100-digit number

.
Try 115 odd numbers near 10^{100}.

About 1/230 100-digit numbers are prime.

Break input message M into numerical blocks smaller than n.