The word cent comes from a Latin word that means “one hundred,” so you might think that the many-legged creature called the centipede has 100 legs. But it’s only a rare centipede that has exactly 100 legs.
All centipedes have one pair of legs for each body segment; so if a centipede has 20 body segments, it will have 40 legs. Most centipedes have either 30 or 42 legs, but a few have more than 160.
The word millipede means “a thousand legs.” But like its cousin, the centipede, the millipede doesn’t have the number of legs that its name would suggest.
All millipedes have two pairs of legs for each body segment, and most millipedes have less than 100 segments. In fact, the millipede with the most legs has 355 pairs, or only 710 legs.
You shouldn’t call it a centipede if it only has 30-42 legs. If it’s rare that they have over 100 legs, then don’t call it a centipede just let the 100 legged thing be a good luck charm.