Identify the quantity or vector you want the magnitude of
Use the appropriate formula for the type of quantity
For a 2D vector ((x, y)), compute (sqrt{x^2 + y^2})
For a 3D vector ((x, y, z)), compute (sqrt{x^2 + y^2 + z^2})
For a scalar value, take its absolute value
Substitute the given values into the formula
Simplify the expression
Write the final result with the correct units if needed