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'Tower of Hanoi' printed from https://nrich.maths.org/
Look at the sequence below:
$1, 2, 4, 8, 16...$
Can you describe how to get from one term to the next?
Can you describe the $n^{th}$ term of the sequence?
Now try adding together terms from the sequence:
$1 + 2$
$1 + 2 + 4$
$1 + 2 + 4 + 8$
Do you notice anything interesting?
Can you predict what $1 + 2 + 4 + ... + 64 + 128$ would be? Check to see if you are right.
How could you write the answer to $1 + 2 + 4 + ... + 2^n$?
Justify why your formula works.
Hint for building block B: Think about moving all the discs except the largest one onto the middle peg first.
Hint for Extension question: Current theory and observations suggest that between 13.5 and 14 billion years have elapsed since the Big Bang.