Public information services and documents should be accessible to the widest possible readership. Information in newspapers often takes the form of numerical expressions which pose comprehension problems for people with limited education. A first possible approach to solve this important social problem is making numerical information accessible by rewriting difficult numerical expressions in a simpler way. To obtain guidelines for performing this task automatically, we have carried out a survey in which experts in numeracy were asked to simplify a range of proportion expressions, with three readerships in mind: (a) people who did not understand percentages; (b) people who did not understand decimals; (c) more generally, people with poor numeracy. Responses were consistent with our intuitions about how common values are considered simpler and how the value of the original expression influences the chosen simplification.