What is the weight in newtons of an object that has a mass of 610 mg?

To answer this question, you need to know the gravity power used for this equation. Let assume the gravity is 9.8N/kg. Then to find the mass, you need to multiply the weight with gravitational acceleration. The equation would be:

mass = weight x gravity

mass = 610mg x 10^-6 kg/mg x 9.8N/kg = 5978 x 10^-6 = 5.978 x 10^-3