so there this cheap guy who measures ice cream in kg ... he uses a scale and doens't measure something twice ... he only uses 4 weights and sells ice cream from 1-40 kg what are the values of the weights?
1, 3, 9 and 27 kg.
1 kg: 1 on the LHS, ice cream on the RHS.
2kg: 3 on the LHS, 1 and the ice cream on the RHS.
3kg: 3 on the LHS, ice cream on the RHS.
4kg: 3 and 1 on the LHS ...
5kg: 9 on the LHS, 3 and 1 on the RHS
6kg: 9 on the LHS, 6 on the RHS
And so on.
It's a thinly-disguised way of interpreting numbers in base 3.