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Plutarch's Boxes

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3388

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.

Rod Fractions

Age 11 to 14 Challenge Level:
Terry from Warren Comprehensive School sent us his solution to this problem:

The Red rod is $\frac{1}{4}$ of the Brown rod.
The Green rod is $\frac{2}{3}$ of the Blue rod.
The Pink rod is $\frac{2}{5}$ of the Orange rod.
The Green rod is $\frac{3}{10}$ of the Orange rod.

The method for working out the short rod as a fraction of the long rod is:

When you complete the rows of rods so that they match, the number of long rods is the numerator for the fraction and the number of short rods is the denominator for the fraction.

It is easy to see why this works when you use only one long rod - you can return to the interactivity to see why this works in general.

Well done Terry.


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