4 ms·

You are missing - 24, -2, -1, 1, 2, and 24 for a total of 20.

• cyphar 6y ago
  ±1 doesn't require a prefix, and while in Europe "deci" is used in common parlance for units of power ±2 it's not really used in scientific or engineering terminology globally. I'm also not sure what real quantity you're referring to which requires the power ±24 prefix (yes, the term "yottabyte" exists but no measurement of data capacity uses it).
  • danbruc 6y ago
    ±2 are centi and hecto with centimetre and hectopascal probably being the widest used ones, ±1 are deci and deca with decibel probably being the widest used one. For deca I can also not think of any real usage.