This poem was written by Jon Saxton (an author of math textbooks).

((12 + 144 + 20 + (3 * 4^(1/2))) / 7) + (5 * 11) = 9^2 + 0

Or for those who have trouble with the poem:

A Dozen, a Gross and a Score,

plus three times the square root of four,

divided by seven,

plus five times eleven,

equals nine squared and not a bit more.

Tis a favorite project of mine

A new value of pi to assign.

I would fix it at 3

For its simpler, you see,

Than 3 point 1 4 1 5 9.

(The Lure of the Limerick by W.S. Baring-Gould, p.5. Attributed to Harvey L. Carter).

If inside a circle a line

Hits the center and goes spine to spine

And the lines length is d

the circumference will be

d times 3.14159

If (1+x) (real close to 1)

Is raised to the power of 1

Over x, you will find

Heres the value defined:
2.718281…

Heres a limerick – looks better on paper.

/3
/
| 2 3 x 3.14 3_
| z dz x cos( ———-) = ln (/e )
| 9
/
1

Which, of course, translates to:

Integral z-squared dz

from 1 to the square root of 3

times the cosine

of three pi over 9

equals log of the cube root of e.

And its correct, too.