How many legs does a shrimp have?

They have 5 pairs of "legs" (-> 10 legs) [paraeopodes], but only use 6 of them for walking. 2 pairs have little pincers. They also have 5 pairs (-> 10 legs) of swimminglegs [pleopodes]. This gives them 20 legs or 10 pairs out of which they use 6 or 3 pairs for walking.