Make a set of numbers that use all the digits from 1 to 9, once and
once only. Add them up. The result is divisible by 9. Add each of
the digits in the new number. What is their sum? Now try some. . . .
Where will the point stop after it has turned through 30 000
degrees? I took out my calculator and typed 30 000 ÷ 360. How
did this help?
Which set of numbers that add to 10 have the largest product?
Use the clocks to investigate French decimal time in this problem.
Can you see how this time system worked?
If a sum invested gains 10% each year how long before it has
doubled its value?
Investigate what happens if we create number patterns using some simple rules.
Start with any triangle T1 and its inscribed circle. Draw the
triangle T2 which has its vertices at the points of contact between
the triangle T1 and its incircle. Now keep repeating this. . . .
Nowadays the calculator is very familiar to many of us. What did
people do to save time working out more difficult problems before
the calculator existed?