David Morice in WW 96-179 introduced acrostic equations with the only possible perfect example, TEN = Twenty + Eighty - Ninety. It's purity is perhaps best left unpolluted by more forced examples. But nooo, I couldn't refrain from offering variously flawed solutions for the other number names.
Word Ways: Vol. 41
, Article 25.
Available at: http://digitalcommons.butler.edu/wordways/vol41/iss2/25