A very magical teacher had a student select a two-digit ber between 50 and 100 and write it on the board out of view
of the instructor. Next, the student was asked to add 76 to the
number, producing a three-digit sum. If the digit in the hun-
dreds place is added to the remaining two-digit number and
this result is subtracted from the original number, the answer
is 23, which was predicted by the instructor. How did the
instructor know the answer would be 23? Note: This problem
is dedicated to my friend Bill Leonard of Cal State, Fullerton.
His favorite number is 23.