MathCentre is a very large repository of tutorial videos, interactive assessments and PDF handouts to help with maths topics, roughly at A-level. This link is to a range of topics selected as relevant to Economics. The materials are categorised by area (such as Algebra, Arithmetic and Differentiation) and by individual topic.
Assessment Materials in Maths for Economists
Mathematics for economists is a course webpage produced by Dieter Balkenborg of the University of Exeter, the 2008 version of the course was taught by Juliette Stephenson. The material includes lecture slides, class exercises and solutions, homework tasks, and exam papers, usually made available as PDF files. Also includes links to previous versions of the course stretching back to 2001.
Three short (15 minute) tests are archived here, using a cross between multiple-choice and multiple-response questions, totally 26 questions.
This is an online tool that creates paper exams in the key mathematical skills required for Economics. It generates questions randomly, lets you choose which ones to include and then print out separate question and answer sheets.