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Lastly - Well

What are the last two digits of 2^(2^2003)?

Counting Factors

Is there an efficient way to work out how many factors a large number has?

Summing Consecutive Numbers

15 = 7 + 8 and 10 = 1 + 2 + 3 + 4. Can you say which numbers can be expressed as the sum of two or more consecutive integers?

One to Eight

Age 11 to 14 Challenge Level:

Here are some 'funny factorisations'. Complete the following expressions so that each one gives a four digit number as the product of two two digit numbers and uses the digits $2$ to $9$ once and only once.

** $\times$ ** $= 4876$
** $\times$ ** $= 5394$

Now do the same with the digits $1$ to $8$ to complete the following expressions.

** $\times$ ** $= 1368$
$5$* $\times$ $6$* $=$ ****
$52$ $\times$ ** $=$ ****

Is there more than one solution?