The website dyslexia-parent.com is really a useful website.
Under the heading Dyslexia Parents Resources - sub-heading math/s, it provides the practical tips for teaching maths to the dyslexics.

In the dyslexia online magazine under the heading 'dyslexia and maths' many useful tips for learning maths are provided.

www.multiplication.com is very useful for learning multiplication tables.

www.dyslexia-teacher.com is another useful site.