Maths Puzzles for KS3/KS4
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The stupid gardener

Resources

Teaching notes

To find the solution, students can either add all the numbers from 1 to 100, and double this for the return journey, or add all of the even numbers from 2 to 200.

Rather than simply adding all 100 numbers together, a quicker way of working out the total is to pair the numbers up, ie 1 + 99, 2 + 98, 3 + 97, and so on up to 49 + 51. This gives 49 x 100 = 4900. Then add the 100 and the 50, and double the total to include the return journeys.

Solution

The total is 10,100 m, or 10.1 km.

Extension

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