Stage:5 Challenge Level:
My new phone number has seven digits and I can never remember it. My friend says she remembers it because if the last four digits are placed in front of the remaining three you get one more than twice my number!
(The article on Euclid's Algorithm might help with this problem.)
Number bases. Factors and multiples. Integers. Working systematically. Place value. Addition & subtraction. Diophantine equations. Euclid's algorithm. Multiplication & division. Long problems.
Published September 1999.
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