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Gaxinta

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?

Thirty Six Exactly

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

Strange Numbers

All strange numbers are prime. Every one digit prime number is strange and a number of two or more digits is strange if and only if so are the two numbers obtained from it by omitting either its first or its last digit. Find all strange numbers.

One to Eight

Age 11 to 14 Challenge Level:

Sue from CBEC Basingstoke sent the following explanation to the first question:

** X ** = 4876
If you write 4876 as a product of prime factors you get 2 x 2 x 23 x 53
From this you need to find two, two digit numbers that use the digits 2, 3, 5 and 9
This has to be 2 x 2 x 23 = 92 and 53

We also received correct solutions from Jenny, Greenian, Rachael, Jacqui and Sam, from The Mount School, and Debbie from Forres Academy. Well done to you all.

53 x 92 = 4876
62 x 87 = 5394

24 x 57 = 1368
58 x 64 = 3712
52 x 34 = 1768

We'd like to hear from anyone who would like to explain how they solved these problems.
We are always interested in the reasoning that has helped you reach your solutions.