Number Detective

Follow the clues to find the mystery number.

Six Is the Sum

What do the digits in the number fifteen add up to? How many other numbers have digits with the same total but no zeros?

(w)holy Numbers

A church hymn book contains 700 hymns. The numbers of the hymns are displayed by combining special small single-digit boards. What is the minimum number of small boards that is needed?

Coded Hundred Square

Stage: 2 Challenge Level:

Where could you start?
What might the first numbers look like?
What might the last number look like?
What do you know about the multiples of $11$?
What will be the same in each column?
What will be the same for the first nine numbers in each row?