Math CentralQuandaries & Queries


Question from Grace, a student:

91 meters of cotton goes round the cotton reel. About how many times does the cotton go round the reel?
Give your answer to the nearest ten.
(The Diameter of the cylinder is 3cm)

Hi Grace,

I assume this is cotton thread. If it is cotton fabric then each time you go around the cylinder the diameter increases by twice the thickness of the fabric.

If the diameter of a circle is 3 cm what is its circumference? You have 91 meters or 9100 centimeters of thread? How many times can you wrap this around the spool?


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