You may also like

problem icon

Look Before You Leap

Relate these algebraic expressions to geometrical diagrams.

problem icon

Modular Fractions

We only need 7 numbers for modulus (or clock) arithmetic mod 7 including working with fractions. Explore how to divide numbers and write fractions in modulus arithemtic.

problem icon

Stretching Fractions: A Discussion

This article extends and investigates the ideas in the problem "Stretching Fractions".

Can it Be

Age 16 to 18 Challenge Level:

When, if ever, is $${a\over b} + {c\over d} = {a+c\over b+d}$$ where $a$ and $b$ have no factors in common and $c$ and $d$ have no factors in common?
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.
Copyright © 1997 - 2018. University of Cambridge. All rights reserved.
NRICH is part of the family of activities in the Millennium Mathematics Project.