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Each of the problems in this set offers students an opportunity to explore particular numerical cases which give rise to patterns that they may be keen to explain. When they are ready, students can make generalisations, and appreciate the power of algebra to capture the generality in a concise and elegant way.
Multiple Surprises and Square Number Surprises include solutions that have previously been submitted to NRICH, so students may wish to try these problems first and then compare their own approaches with the published ones. Then they could go on to try Tilted Squares and Difference of Two Squares, which are open for them to submit their own solutions.
There are unexpected discoveries to be made about square numbers...
It's easy to work out the areas of most squares that we meet, but what if they were tilted?
What is special about the difference between squares of numbers adjacent to multiples of three?