self Maths Puzzle

21!=510909x21y1709440000

Without calculating 21!, what are the digits marked x and y? explain.

Read Solution (Total 3)

self Other Question

How many letters does the correct answer to this puzzle contain? The sum of N real numbers (not necessarily unique) is 20. The sum of the 3 smallest of these numbers is 5. The sum of the 3 largest is 7. What is N?