Today's Brain Game gives you five letters of the English alphabet, leaving 21 unused. One of those 21 is the answer to today's puzzle. Good luck!

What's the next letter in this sequence?

K, M, G, T, P, ?

Here is the SOLUTION.

THE SOLUTION:

E.

Technically, the letters represent "the first six entries in the International System of Units prefixes for unit multiples." But if you don't speak geek:

They stand for 1,000 times the next-lowest units of measurement.

K = kilo (1,000 units)
M = mega (1000K units)
G = giga (1000M units)
T = tera (1000G units)
P = peta (1000T units)... then our answer is:
E = exa (1000P units).

NOTE: In binary systems (like those used for computer memory), the multiple is 1024 instead of 1000, but the prefixes are the same.