**From New Scientist #2484, 29th January 2005**

I have just written down five different two-figure numbers:

• my age

• my house number

• the sum of those first two numbers

• the difference between those first two numbers

• half of one of those first four numbers

However, I have written the names of the numbers in words rather than use figures. Surprisingly, each of the five numbers has precisely the same number of letters in its name.

What were the last three numbers?

[enigma1325]

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This Python code uses the

int2words()routine from theenigma.pylibrary. It runs in 35ms.Solution:The last three numbers are: 86, 44 and 22.The age and house number are 21 and 65, but we have no way to distinguish them, so we don’t know which is which. Their sum is 86, their difference is 44, and half of 44 is 22. “Twenty-one”, “sixty-five”, “eighty-six”, “forty-four” and “twenty-two” all have 9 letters.