Editing Hash function (section)

=== Mid-squares ===
A mid-squares hash code is produced by squaring the input and extracting an appropriate number of middle digits or bits.  For example, if the input is {{Val|123456789}} and the hash table size {{Val|10000}}, then squaring the key produces {{Val|15241578750190521}}, so the hash code is taken as the middle 4 digits of the 17-digit number (ignoring the high digit) 8750.  The mid-squares method produces a reasonable hash code if there is not a lot of leading or trailing zeros in the key.  This is a variant of multiplicative hashing, but not as good because an arbitrary key is not a good multiplier.