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Special Numbers

My two digit number is special because adding the sum of its digits to the product of its digits gives me my original number. What could my number be?

Your Number Is...

Think of a number and follow the machine's instructions... I know what your number is! Can you explain how I know?

First Forward Into Logo 6: Variables and Procedures

Learn to write procedures and build them into Logo programs. Learn to use variables.

Your Number Was...

Age 11 to 14
Challenge Level

This problem follows on from Your Number Is...
 

Press the button in the interactivity below to investigate what this machine does:

Try starting with other numbers - maybe decimals or negative numbers.

How is the machine working out your starting numbers?

Can you devise your own set of instructions so you can work out someone else's starting numbers in the same way?
The NRICH Project aims to enrich the mathematical experiences of all learners. To support this aim, members of the NRICH team work in a wide range of capacities, including providing professional development for teachers wishing to embed rich mathematical tasks into everyday classroom practice.
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NRICH is part of the family of activities in the Millennium Mathematics Project.