Imagine a strip with a mark somewhere along it. Fold it in the
middle so that the bottom reaches back to the top. Stetch it out to
match the original length. Now where's the mark?
However did we manage before calculators? Is there an efficient way
to do a square root if you have to do the work yourself?
It's like 'Peaches Today, Peaches Tomorrow' but interestingly
Find the numbers in this sum
Vedic Sutra is one of many ancient Indian sutras which involves a
cross subtraction method. Can you give a good explanation of WHY it
A 3 digit number is multiplied by a 2 digit number and the
calculation is written out as shown with a digit in place of each
of the *'s. Complete the whole multiplication sum.
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. . . .
Choose any 4 whole numbers and take the difference between
consecutive numbers, ending with the difference between the first
and the last numbers. What happens when you repeat this process
over and. . . .
What day of the week were you born on? Do you know? Here's a way to
Countries from across the world competed in a sports tournament. Can you devise an efficient strategy to work out the order in which they finished?
Scheduling games is a little more challenging than one might desire. Here are some tournament formats that sport schedulers use.
How would you judge a competition to draw a freehand square?
The number 10112359550561797752808988764044943820224719 is called a
'slippy number' because, when the last digit 9 is moved to the
front, the new number produced is the slippy number multiplied by
Some 4 digit numbers can be written as the product of a 3 digit
number and a 2 digit number using the digits 1 to 9 each once and
only once. The number 4396 can be written as just such a product.
Can. . . .
This addition sum uses all ten digits 0, 1, 2...9 exactly once.
Find the sum and show that the one you give is the only
This challenge is to make up YOUR OWN alphanumeric. Each letter
represents a digit and where the same letter appears more than once
it must represent the same digit each time.
Watch our videos of multiplication methods that you may not have met before. Can you make sense of them?
A geometry lab crafted in a functional programming language. Ported
to Flash from the original java at web.comlab.ox.ac.uk/geomlab
When the number x 1 x x x is multiplied by 417 this gives the
answer 9 x x x 0 5 7. Find the missing digits, each of which is
represented by an "x" .
Amazing as it may seem the three fives remaining in the following
`skeleton' are sufficient to reconstruct the entire long division
Read this article to find out the mathematical method for working out what day of the week each particular date fell on back as far as 1700.