THE NUMBER 916238457 IS AN EXAMPLE OF A NINE-DIGIT NUMBER WHICHTRY...

3. The number 916238457 is an example of a nine-digit number which

try all the problems.

contains each of the digits 1 to 9 exactly once. It also has the property

that the digits 1 to 5 occur in their natural order, while the digits 1

• Each question carries 10 marks. However, earlier

to 6 do not. How many such numbers are there?

questions tend to be easier. In general you are

advised to concentrate on these problems first.