Square Root

Square Root shoots numbers up to five. The number (1-5) will be squared, doing 1-25nds of damage depending on the number.

Suburban Almanac Entry
Square Root is a massive nerd. You could probably already tell by his name - did you know he takes nerd as a compliment?

Plant Food
It shoots a 3 sixes, doing 36 damage (because 6 squared = 36). In total, though, it would do 108 damage.

Strategies
Don't use it too frequently throughout your lawn, as it could lead to your demise (because you know how RNG hates everyone). To be safe, try to keep to under 3 rows.

Trivia

 * Square Root's name is literally something you would do in math, hence it's ability.