Leigh Mercer

Leigh Mercer (1893–1977) was a British wordplay and recreational mathematics expert.

Palindrome
Mercer is best known for devising the palindrome "A man, a plan, a canal: Panama!".

Mathematical limerick
The following mathematical limerick is attributed to him:
 * $$	\frac{12 + 144 + 20 + 3\cdot \sqrt{4}}{7} + (5 \times 11) = 9^2+0$$

This is read as follows:
 * A dozen, a gross, and a score
 * Plus three times the square root of four
 * Divided by seven
 * Plus five times eleven
 * Is nine squared and not a bit more.