![Gift Stacks](/sites/default/files/styles/medium/public/thumbnails/content-98-12-penta4-icon.jpg?itok=GOC_4vd2)
Multiplication and division
![Gift Stacks](/sites/default/files/styles/medium/public/thumbnails/content-98-12-penta4-icon.jpg?itok=GOC_4vd2)
![Clever Santa](/sites/default/files/styles/medium/public/thumbnails/content-98-12-penta3-icon.jpg?itok=XIfhs7O_)
problem
Clever Santa
All the girls would like a puzzle each for Christmas and all the
boys would like a book each. Solve the riddle to find out how many
puzzles and books Santa left.
![Clock Face](/sites/default/files/styles/medium/public/thumbnails/content-98-11-penta4-icon.png?itok=YJeEwTMl)
problem
Clock Face
Where can you draw a line on a clock face so that the numbers on
both sides have the same total?
![A One in Seven Chance](/sites/default/files/styles/medium/public/thumbnails/content-97-12-15plus2-icon.jpg?itok=FAES21uh)
![A Conversation Piece](/sites/default/files/styles/medium/public/thumbnails/content-03-09-penta3-icon.gif?itok=QBBFIGhV)
problem
A Conversation Piece
Take the number 6 469 693 230 and divide it by the first ten prime
numbers and you'll find the most beautiful, most magic of all
numbers. What is it?
![1, 2, 3, 4, 5](/sites/default/files/styles/medium/public/thumbnails/content-03-09-penta2-icon.gif?itok=iIEqXyLH)
problem
1, 2, 3, 4, 5
Using the numbers 1, 2, 3, 4 and 5 once and only once, and the
operations x and ÷ once and only once, what is the smallest
whole number you can make?
![The Number Crunching Machine](/sites/default/files/styles/medium/public/thumbnails/content-03-07-penta1-icon.gif?itok=EpH7NMxI)
problem
The Number Crunching Machine
Put a number at the top of the machine and collect a number at the
bottom. What do you get? Which numbers get back to themselves?
![Sept03 Sept03 Sept03](/sites/default/files/styles/medium/public/thumbnails/content-03-09-six10-icon.gif?itok=iagJGRBC)
![Which is quicker?](/sites/default/files/styles/medium/public/thumbnails/content-03-09-letme2-icon.gif?itok=Txz6gtCb)
problem
Which is quicker?
Which is quicker, counting up to 30 in ones or counting up to 300 in tens? Why?
![Largest product](/sites/default/files/styles/medium/public/thumbnails/content-96-11-six6-icon.png?itok=visW6w7i)