You may also like

problem icon


A number N is divisible by 10, 90, 98 and 882 but it is NOT divisible by 50 or 270 or 686 or 1764. It is also known that N is a factor of 9261000. What is N?

problem icon

Thirty Six Exactly

The number 12 = 2^2 3 has 6 factors. What is the smallest natural number with exactly 36 factors?

problem icon

Factoring Factorials

Find the highest power of 11 that will divide into 1000! exactly.

Pairing Up

Stage: 3 Short Challenge Level: Challenge Level:1

As the product of each pair has the same value, this value must be product of the smallest and largest numbers, that is $5\times72$.

So the number which is paired with $10$ is $5\times72\div10$, that is $36$.

This problem is taken from the UKMT Mathematical Challenges.