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Mathematical reasoning & proof. Describing patterns and sequences. Infinity. Video. Creating and manipulating expressions and formulae. Visualising. Generalising. Odd and even numbers. Factors and multiples. Arithmetic sequences.There are 45 results
Broad Topics > Fractions, Decimals, Percentages, Ratio and Proportion > Fractions
Egyptian Fractions
Age 11 to 14 Challenge Level:
The Egyptians expressed all fractions as the sum of different unit fractions. Here is a chance to explore how they could have written different fractions.
Keep it Simple
Age 11 to 14 Challenge Level:
Can all unit fractions be written as the sum of two unit fractions?
More Twisting and Turning
Age 11 to 16 Challenge Level:
It would be nice to have a strategy for disentangling any tangled ropes...
Harmonic Triangle
Age 14 to 16 Challenge Level:
Can you see how to build a harmonic triangle? Can you work out the next two rows?
Twisting and Turning
Age 11 to 14 Challenge Level:
Take a look at the video and try to find a sequence of moves that will untangle the ropes.
Farey Sequences
Age 11 to 14 Challenge Level:
There are lots of ideas to explore in these sequences of ordered fractions.
Unit Fractions
Age 11 to 14 Challenge Level:
Consider the equation 1/a + 1/b + 1/c = 1 where a, b and c are natural numbers and 0 < a < b < c. Prove that there is only one set of values which satisfy this equation.
Cuisenaire Environment
Age 5 to 16 Challenge Level:
An environment which simulates working with Cuisenaire rods.
What a Joke
Age 14 to 16 Challenge Level:
Each letter represents a different positive digit AHHAAH / JOKE = HA What are the values of each of the letters?
Fracmax
Age 14 to 16 Challenge Level:
Find the maximum value of 1/p + 1/q + 1/r where this sum is less than 1 and p, q, and r are positive integers.
Mathematical Swimmer
Age 11 to 14 Challenge Level:
Can you work out how many lengths I swim each day?
Diminishing Returns
Age 11 to 14 Challenge Level:
How much of the square is coloured blue? How will the pattern continue?
Stretching Fractions: A Discussion
Age 14 to 18
This article extends and investigates the ideas in the problem "Stretching Fractions".
The Cantor Set
Age 11 to 14 Challenge Level:
Take a line segment of length 1. Remove the middle third. Remove the middle thirds of what you have left. Repeat infinitely many times, and you have the Cantor Set. Can you picture it?
Circuit Training
Age 14 to 16 Challenge Level:
Mike and Monisha meet at the race track, which is 400m round. Just to make a point, Mike runs anticlockwise whilst Monisha runs clockwise. Where will they meet on their way around and will they ever. . . .
How Long Is the Cantor Set?
Age 11 to 14 Challenge Level:
Take a line segment of length 1. Remove the middle third. Remove the middle thirds of what you have left. Repeat infinitely many times, and you have the Cantor Set. Can you find its length?
Stretching Fractions
Age 14 to 16 Challenge Level:
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?
The Greedy Algorithm
Age 11 to 14 Challenge Level:
The Egyptians expressed all fractions as the sum of different unit fractions. The Greedy Algorithm might provide us with an efficient way of doing this.
Peaches Today, Peaches Tomorrow...
Age 11 to 14 Challenge Level:
A monkey with peaches, keeps a fraction of them each day, gives the rest away, and then eats one. How long can his peaches last?
History of Fractions
Age 7 to 14
Who first used fractions? Were they always written in the same way? How did fractions reach us here? These are the sorts of questions which this article will answer for you.
Fractions and Percentages Card Game
Age 11 to 16 Challenge Level:
Can you find the pairs that represent the same amount of money?
3388
Age 11 to 14 Challenge Level:
Using some or all of the operations of addition, subtraction, multiplication and division and using the digits 3, 3, 8 and 8 each once and only once make an expression equal to 24.
Tangles
Age 11 to 16
A personal investigation of Conway's Rational Tangles. What were the interesting questions that needed to be asked, and where did they lead?
Couples
Age 11 to 14 Challenge Level:
In a certain community two thirds of the adult men are married to three quarters of the adult women. How many adults would there be in the smallest community of this type?
Rationals Between...
Age 14 to 16 Challenge Level:
What fractions can you find between the square roots of 65 and 67?
Equal Temperament
Age 14 to 16 Challenge Level:
The scale on a piano does something clever : the ratio (interval) between any adjacent points on the scale is equal. If you play any note, twelve points higher will be exactly an octave on.
Tiny Nines
Age 14 to 16 Challenge Level:
What do you notice about these families of recurring decimals?
Rod Fractions
Age 7 to 14 Challenge Level:
Pick two rods of different colours. Given an unlimited supply of rods of each of the two colours, how can we work out what fraction the shorter rod is of the longer one?
Do Unto Caesar
Age 11 to 14 Challenge Level:
At the beginning of the night three poker players; Alan, Bernie and Craig had money in the ratios 7 : 6 : 5. At the end of the night the ratio was 6 : 5 : 4. One of them won $1 200. What were the. . . .
Matching Fractions, Decimals and Percentages
Age 7 to 14 Challenge Level:
Can you match pairs of fractions, decimals and percentages, and beat your previous scores?
Water Lilies
Age 11 to 14 Challenge Level:
There are some water lilies in a lake. The area that they cover doubles in size every day. After 17 days the whole lake is covered. How long did it take them to cover half the lake?
Six Notes All Nice Ratios
Age 14 to 16 Challenge Level:
The Pythagoreans noticed that nice simple ratios of string length made nice sounds together.
Plutarch's Boxes
Age 11 to 14 Challenge Level:
According to Plutarch, the Greeks found all the rectangles with integer sides, whose areas are equal to their perimeters. Can you find them? What rectangular boxes, with integer sides, have. . . .
Pythagoras’ Comma
Age 14 to 16 Challenge Level:
Using an understanding that 1:2 and 2:3 were good ratios, start with a length and keep reducing it to 2/3 of itself. Each time that took the length under 1/2 they doubled it to get back within range.
Teaching Fractions with Understanding: Part-whole Concept
Age 5 to 14
Written for teachers, this article describes four basic approaches children use in understanding fractions as equal parts of a whole.
Terminating or Not
Age 11 to 14 Challenge Level:
Is there a quick way to work out whether a fraction terminates or recurs when you write it as a decimal?
F'arc'tion
Age 14 to 16 Short Challenge Level:
At the corner of the cube circular arcs are drawn and the area enclosed shaded. What fraction of the surface area of the cube is shaded? Try working out the answer without recourse to pencil and. . . .
Counting Fish
Age 14 to 16 Challenge Level:
I need a figure for the fish population in a lake. How does it help to catch and mark 40 fish?
Racing Odds
Age 11 to 14 Challenge Level:
In a race the odds are: 2 to 1 against the rhinoceros winning and 3 to 2 against the hippopotamus winning. What are the odds against the elephant winning if the race is fair?
Bull's Eye
Age 11 to 14 Challenge Level:
What fractions of the largest circle are the two shaded regions?
The Genes of Gilgamesh
Age 14 to 16 Challenge Level:
Can you work out the parentage of the ancient hero Gilgamesh?
NRICH is part of the family of activities in the Millennium Mathematics Project.