Hi, you've asked an incomplete question. However, I assumed you are referring to the article found on the Scientific American website.
Explanation:
<em>Remember,</em> according to that article we are told that scientists notice that these insects have a long nymphal (immature form before becoming adults) stage, one that can last up to 13 to 17 years on the ground before they leave the ground looking for mating partners.
Because it is only after mating occurs at this point that their eggs are laid, that is why scientists believe that cicadas only reproduce every 13 or 17 years.
High tide or Neap tides which are normally really high.
Explanation:
83,000 is 8.3x10^4 in standard form
when it's a positive move decimal to the right as many as exponent say
if it's negative move decimal to left and and zeros till you move what exponent says
Number of neutrons = Atomic mass - Atomic number (number of protons)
Hope that helps!