RIDDLE for all you maths lovers?

Question

Back in the old day(dont ask how long ago), a shopkeeper used to measure the weight of his products using four stones and only four stones, each stone has a different weight to it. Each stone had a weight between 1kg and 40kg. Using these four stones he was then able to weigh any product between 1kg and 40kg.

WHAT WERE THE WEIGHTS OF THESE FOUR STONES????

Answer 1

1KG, 3KG, 9KG, 27KG

=]

Answer 2

lOl i am stumped!

But i know the answer is between 1-30

Answer 3

By using the weights on both sides..

3kg  4kg  15kg   21kg

Answer 4

Ay... You already posted the answer!!!

Anyway, can I have 10 points for proving your answer for you?

4 Stones

1kg - 3kg - 9kg - 27kg

Number in ( ) is the weight of an item to be measured.  You add to it the stone(s) of certain weight to balance out with the weight of stones  on the right side.

(1) <---> 1

(2) + 1 <---> 3

(3) <---> 3

(4) <---> 1+ 3

(5) + 1+ 3  <--->  9

(6) + 3  <---> 9

(7) + 3 <---> 1+ 9

(8) + 1 <---> 9

(9) <---> 9

(10) <---> 1+ 9

(11) + 1 <---> 3 + 9

(12) <---> 3 + 9

(13) <---> 1+ 3+ 9

(14) + 1+ 3 + 9 <---> 27

(15) + 3 + 9  <---> 27

(16) + 3 + 9 <---> 27 +1

(17) + 1 + 9 <---> 27

(18) + 9 <---> 27

(19) + 9 <---> 27+ 1

(20) + 9 + 1 <---> 27+ 3

(21) + 9 <---> 27+ 3

(22) + 9 <---> 27+ 3 + 1

(23) + 3 + 1 <---> 27

(24) + 3 <---> 27

(25) + 3 <---> 27+ 1

(26) + 1 <---> 27

(27) <---> 27

(28) <---> 27 + 1

(29) + 1 <---> 27+ 3

(30) <---> 27 + 3

(31) <---> 1+ 3 + 27

(32) + 1+ 3 <---> 27+ 9

(33) + 3 <---> 27+ 9

(34) + 3 <---> 1+ 9 + 27

(35) + 1 <---> 9 + 27

(36) <--->  9 + 27

(37) <---> 1+ 9 + 27

(38) + 1 <---> 27+ 9+ 3

(39) <---> 27+ 9 + 3

(40) <---> 1+ 3 + 9 + 27

Answer 5

If he uses them to measure the weight of the products and doesn't use a scale, how does he know how much they weigh?