Numerical reasoning means more than just performing mathematical calculations. In fact, calculators are allowed- because you're calculation skills are not being measured.
Instead, the numerical test is more about handling data. In each question, you'll be presented with a graphic representation of information: a table, grpah, or chart. You will need to answer questions about the data, often requiring you to understand and utilize basic mathematical concepts like ratios, percentages, and fractions.
The BlackRock Numerical Test contains 20 questions, with one minute alloted for each question.