The numbers of people sacrificed by the Aztecs is a mystery today and will probably remain a mystery, unless more archeological evidence is uncovered. Whether only a few thousand of victims were sacrificed each year, or 250,000 as some scholars say, few human remains such as bones have been found at Templo Mayor or other Aztec temples.

A couple of dozen skeletons and a few thousand loose bones and skulls do not add up to 250,000 or 20,000 or whatever number is cited.Evidence of human sacrifice comes from both the Aztecs themselves, their art and codices containing their writings, and from the Spanish conquerors. However, it is safe to say that the Spanish could easily have exaggerated the numbers killed to make the Aztecs seem more savage and brutal than they actually were. 
They killed many people as sacrifice