# B.7 Examples for Chapter 9

# Example 22

Suppose you need to find a large random prime of 50 digits. Here is one way. The function `nextprime`

finds the next prime greater than $x\text{.}$ The function `rand(a..b)()`

gives a random integer between $a$ and $b\text{.}$ Combining these, we can find a prime:

`> nextprime(rand($10^49$..$10^50$)())`

`73050570031667109175215303340488313456708913284291`

If we repeat this procedure, we should get another prime:

`> nextprime(rand($10^49$..$10^50$)())`

`97476407694931303255724326040586144145341054568331`

# Example 23

Suppose you want to change the text *hellohowareyou* to numbers:

`> text2num("hellohowareyou")`

`805121215081523011805251521`

Note that we are now using *a = 1, b = 2, ..., z = 26*, since otherwise *a*’s at the beginnings of messages ...

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