what is upper case and lower case character
Letter case Letter case (or just case) is the distinction between the letters that are in larger upper case (also uppercase, capital letters, capitals, caps, large letters, or more formally majuscule) and smaller lower case (also lowercase, small letters, or more formally minuscule) in the written representation of certain languages. The writing systems that distinguish between the upper and lower case have two parallel sets of letters, with each letter in one set usually having an equivalent in the other set. The two case variants are alternative representations of the same letter: they have the same name and pronunciation and will be treated identically when sorting in alphabetical order.
United States House of Representatives The United States House of Representatives is the lower chamber of the United States Congress, the Senate being the upper chamber. Together they compose the legislature of the United States.
Exponentiation Any nonzero number raised to the 0 power is 1:[11]
1 + 2 + 3 + 4 + ⋯ which increases without bound as n goes to infinity. Because the sequence of partial sums fails to converge to a finite limit, the series does not have a sum.