Stage: 5 Challenge Level: 
What is the sum of:
$6 + 66 + 666 + 6666 + \cdots + 666666666\cdots6$
where there are $n$ sixes in the last term?
Place value. Mathematical induction. epsilons. Stage 5 - Reviewed 2012. Weekly Challenge. Factorials. Scale factors. Making and proving conjectures. Geometric sequence. Summation of series.
Published March 1998.
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