logo1 logo2
 pzzls menu
 pzzls links
 put the newest|oldest|most difficult|easiest|most popular|least popular puzzles on top
page << 2 3 5 6 >>  
 math puzzle 
starstar 

Number magic

If you multiply me by 2, subtract 1, and read the reverse the result you'll find me. Which numbers can I be?

 mail puzzle permalink
rating 2.3/5
 math puzzle 
starstarstar 

Also having birthday today?

Out of how many people should a group at least consist in order to have that the probability that two persons out of that group are having birthday on the same day, is larger than 1/2? birthday cake

 mail puzzle permalink
rating 2.4/5
 math puzzle 
starstarstarstarstar 

Platonic solids

Show that there exist only five platonic solids (that are objects which are build out of the one sort of regular polygons, like the tetrahedron and the cube). Hint: use that for each solid in three dimensions it holds that the number of vertices + the number of faces is equal to the number of edges + 2. platonic solids

 mail puzzle permalink
rating 2.4/5
 put the newest|oldest|most difficult|easiest|most popular|least popular puzzles on top
page << 2 3 5 6 >>  
 Last changed 21-07-2008
Copyright 1999-2008 pzzls.com
rss