All top consultancies require candidates to be able to solve simple numerical problems without a calculator. This skill is tested as part of the case interview. Many experienced candidates feel that they numeracy has became a little rusty after years of using excel. Here are a few tips and resources to help you brush up this skill.

1. Practice maths everyday

Life gives us plenty of opportunities to multiply or divide numbers, and manipulate percentages. Calculate percentages based on tube stations left on your journeys, laps completed on the treadmill, your share of a restaurant bill and headline figures on your morning paper. If you need a more aggressive regimen, spend 10mn a day solving operations randomly generated with excel.

2. Complete standardized tests

The GMAT and the SAT both have maths sections that can help you practice short problems. There are many web sites to practice these tests. One of them is Grockit.

3. Practice McKinsey’s Problem Solving Test

McKinsey offers 3 samples Problem Solving Tests on its website.

Overall, firms don’t ask candidates to be human calculators. However you should be comfortable doing long divisions, weighted averages and break-even analyses with an interviewer watching over your shoulder.