Skip over navigation

Back of the Queue

Age 11 to 14

ShortChallenge Level Yellow star

Secondary curriculum

Answer: $3$

The last digit comes from $9\times7=63$
So the last digit is $3$
Last digit $0$ - multiples of $5$
Last digit $3$ - remainder of $3$

This problem is taken from the UKMT Mathematical Challenges.

You can find more short problems, arranged by curriculum topic, in our short problems collection.

You may also like

Double Digit

Choose two digits and arrange them to make two double-digit numbers. Now add your double-digit numbers. Now add your single digit numbers. Divide your double-digit answer by your single-digit answer. Try lots of examples. What happens? Can you explain it?

Repeaters

Choose any 3 digits and make a 6 digit number by repeating the 3 digits in the same order (e.g. 594594). Explain why whatever digits you choose the number will always be divisible by 7, 11 and 13.

Big Powers

Three people chose this as a favourite problem. It is the sort of problem that needs thinking time - but once the connection is made it gives access to many similar ideas.