How are his handwriting and spelling?
http://www.ldinfo.com/dyscalculia.htm
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Visual Processing Weakness - This appears to be the most common cause of math difficulty. To really be successful in math you need to be able to visualize numbers and math situations. When a person has a generalized visual processing weakness it is sometimes referred to as a nonverbal learning disability. When this is the cause of a student's math difficulties, spelling and handwriting are often also difficult areas (see dysgraphia). Reading and general writing skills may be relative strengths.
Under strategies:
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3. Read the problem out loud and listen very carefully. This allows you to use your auditory skills (which may be a strength).