Use a calculator: enter the number, then press √ (or type `sqrt(number)`).
Factor into perfect squares:
Find factors that are perfect squares.
Rewrite the number as a product of a perfect square and the rest.
Take the square root of the perfect square and simplify the remaining part.
Simplify using prime factorization:
Write the number as a product of primes.
Pair identical primes into squares.
Take one from each pair outside the radical.
Use the square-root property:
√(a · b) = √a · √b
√(a/b) = √a / √b (for b > 0)
For perfect squares:
Memorize common ones (e.g., √1=1, √4=2, √9=3, √16=4, √25=5, √36=6, √49=7, √64=8, √81=9, √100=10).
For non-perfect squares (approximate):
Use Newton’s method: x₀ = number, then xₙ₊₁ = (xₙ + number/xₙ)/2 until close enough.
Or use a calculator’s decimal approximation.