C.1014. 1! + 2! + 3! + ... + 2015! = N
Find the last two digits of N. (As you probably know, n! means the product of the first n positive whole numbers.)
C.1015. Is there such a positive whole power of 5 in which all ten digits appear and exactly the same number of times?
C.1016. In triangle ABC (see the diagram) AB = AC. We know also that angle BAC is 20 degrees, angle QCB is 50 degrees, and angle PBC is 40 degrees. How big is angle PQC?