The one rupee coin is placed on plain paper. How many coins of the same size can be placed round it
so that each one touches the centre and adjacent coins?
The difference between a two-digit number and the number obtained by interchanging the digits is 36. What is the difference between the sum and the difference of the digits of the number if the ratio between the digits of the number is 1 : 2 ?
frank
"Obvious" is the most dangerous word in mathematics.