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'Odd One Out' printed from http://nrich.maths.org/
Some of the odd ones out may be easier to spot than others.
You might first like to generate lots of sets of the random numbers
so that you can get a feel for the the patterns in the
Start off by looking to see what sorts of things the numbers have
in common and how they may logically be generated. Once you have a
logical method of generation (which is only a guess, of course) you
can check to see whether all but one of the numbers fits that
method of generation. If you think that you have found an
explanation, consider the likelihood of numbers generated by some
other method accidentally fitting your pattern.