I think I'm using the wrong formulas or SOMETHING... Here's the question:

"Two equal charges are separated by 3.7 ´ 10^-10 m.
The force between the charges has a magnitude of 2.37 ´ 10^-3 N. What is the magnitude of q on the charges?"

Here's my work:

F = kc(q1q2/r^2)

2.37 x 10^-3 = 8.99 x 10^9 • q1q2 / (3.7 x 10^-10)^2

F • r^2 = kc • q1q2
F • r^2 / kc = q1q2
2.37 x 10^-3 • (3.7 x 10^-10)^2 / 8.99 x 10^9 = q1q2

q1q2 = 3.61 x 10^-32
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

E = kc • q/r^2

2.37 x 10^-3 = 8.99 x 10^9 • q/(3.7 x 10^-10)^2
2.37 x 10^-3 / 8.99 x 10^9 = q/(3.7 x 10^-10)^2
2.37 x 10^-3 / 8.99 x 10^9 • (3.7 x 10^-10)^2 = q

q = 3.61 x 10^-32

PLEASE, PLEASE, PLEASE tell me what I'm doing wrong!!!

Thank you very much. :)

I answered below. You calculated q^2

Take the square root to get q.