When solving for square roots and cube roots, it's very helpful to know many of the perfect squares and perfect cubes.

The first 25 perfect squares are

1, 4, 9, 16, 25, 36, 49, 64, 81, 100, 121, 144, 169, 196, 225, 256, 289, 324, 361, 400, 441, 484, 529, 576, 625

The first 10 perfect cubes are

1, 8, 27, 64, 125, 216, 343, 512, 729, 1000

Knowing these will be very helpful and they aren't hard to memorize.