Drop an egg carefully into a deep saucepan full of cold water.
If the egg sinks to the bottom at once and lies on its side, it is fresh.
If the egg sways about on one end, nearly upright but still in the water, it is not fresh but still usable.
If the egg bobs promptly to the surface and floats, it is spoiled.
Note that since you should not wash the eggs if you want to store them (as said stated in Tip for Keeping Eggs Fresh, #2), you should only perform this test just prior to using the eggs.