# Wrong division, right result

If we divide in the following way (why MathJax \cancel doesn't work on this page?): $$\require{cancel} \frac{1\cancel{\color{red}{6}}}{\cancel{\color{red}{6}}4}=\frac{1}{4}\qquad\text { dividing'' by 6}$$ we obtain the correct result. Another example is $$\frac{1\color{red}{6}\color{cyan}{3}}{\color{cyan}{3}2\color{red}{6}}=\frac12.$$ Is there a method of finding more such examples?

Edit: I wish to thank @amWhy for the immediate help. I am leaving the unchanged question to future users with the same problem.

• You need to declare it before using it (only one such declaration needed: $\require{cancel}$. – Namaste Jul 16 '18 at 15:29
• @amWhy Is \require for a package or a command? (For the future usage). – Przemysław Scherwentke Jul 16 '18 at 15:31
• Any fraction that includes two multiples of $10$ work if you take away the $0$'s. – RayDansh Jul 16 '18 at 15:32
• \require requires a package. Of course it only works for some packages. – Daniel Fischer Jul 16 '18 at 15:37
• This is called "Anomalous Cancellation". Relevant pages: oeis.org/A159975 mathworld.wolfram.com/AnomalousCancellation.html and benvitalenum3ers.wordpress.com/2012/03/17/… (the last one just because it gave me the term) – barrycarter Jul 16 '18 at 15:38