Mathematical puzzles

Puzzles, situation puzzles and recreational mathematics.

situation puzzles and recreational mathematics. Neuron juice

Neuron juice.

The important thing is not to stop questioning. (Albert Einstein.)



9. Three friends with economic difficulties share a coffee that costs 30 coins , so everyone puts 10 .
When you go to ask for a discount and pay the owner cut them 5 coins each taking a penny and leaving on a common background.
Later accounts do and say,
Each has paid nine coins have spent so 9x3 = 27 coins with both the background make 29 where the coin is missing ?




No missing coin, there is only one miscalculation , the two coins fund should not add them to the amount paid , but subtract the correct operation would be 9x3 = 27 coins paid 27-2 = 25 coins worn.