Follow the clues to find the mystery number.
What do the digits in the number fifteen add up to? How many other
numbers have digits with the same total but no zeros?
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?
Use counters or scraps of paper with the digits $0 - 9$ written on them.
Make a list of $3$ consecutive numbers $0 - 9$ remembering that $3$ has already been accounted for.
What could the ones digit of the product be if the multiplication is by $3$?
Which consecutive numbers could be in the four-digit number?
Which other digit could appear in the four-digit number?