^^^ yep, good solution.
in general, if you don't understand the theory behind a DS problem, immediately begin TESTING CASES.
* some problems can only be solved by testing cases (most conspicuously problems that specify integer solutions, but certainly not just those ones).
* even if you don't see the patterns in the problem, you'll often be able to discover those patterns by testing cases.
the latter of these is super important for your studying, too -- that's a big way of learning how things work in these problems!
e.g., in the expression in statement (1) above, the term 10k^2 is a multiple of 10, and so ends in 0.
... but if you don't figure that out right away, all you have to do is test a few cases and it'll be super obvious. and then you can remember it for next time.
Ron has been teaching various standardized tests for 20 years.
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Pueden hacerle preguntas a Ron en castellano
Potete chiedere domande a Ron in italiano
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Quand on se sent bien dans un vêtement, tout peut arriver. Un bon vêtement, c'est un passeport pour le bonheur.
Yves Saint-Laurent
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