# Advent calendar 2017

## 21 December

The factors of 6 (excluding 6 itself) are 1, 2 and 3. \(1+2+3=6\), so 6 is a

*perfect number*.Today's number is the only three digit perfect number.

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The factors of 6 (excluding 6 itself) are 1, 2 and 3. \(1+2+3=6\), so 6 is a *perfect number*.

Today's number is the only three digit perfect number.

Not Roman numerals

Breaking Chocolate

Square and cube endings

List of all puzzles