It’s not a fancy number, fully of mystery. It’s not even accurate in the teeth rhyme as most adult humans have 32 teeth, though that is variable. What’s not really variable is that the number should be divisible by four for bilateral and top-bottom symmetry. Shall we chalk that up to scansion?

• 5.030 Thirty white horses on a red hill,
• 7.075 The Great Goblin was there with thirty or forty armed guards.
• 8.012 I should have thought it was thirty at least,