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Sunday Times Teaser 2629 – Random Road

by Danny Roth

The 99 houses along Random Road lie on one side only but are not numbered from 1 to 99 in the normal way.

The person who numbered the houses gave the first house a number equal to his age in years and then repeatedly added this number to give consecutive houses their numbers by ignoring multiples of 100 in the numbers produced.

Luckily each house got a different number and George’s number was the same as that he would have had if the houses had been numbered normally.

Luckily each house got a different number and George’s number was the same as that he would have had if the houses had been numbered normally. But he noticed that the house next door had a number like theirs but with the two digits in reverse order.

What is George’s number and how old was the person who put up the numbers?

One Comment Leave one →
  1. brian gladman permalink

    I had Internet problems yesterday so my apologies for the delay in posting.

    It turns out that this teaser is ambiguous since the phrase “the next door house had a number like theirs but with the two digits in reverse order” could mean either “a next door house has this house’s number but with its digits reversed”, or “a next door house has its normal number but with its digits reversed”.

    The code below finds a solution for each of these interpretations:

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