Flashcards for 100s Complements

After understanding the theory, improvement in mental maths comes from specific focused practice. This tool is designed to help memorize the complements for 2-digit numbers. For example, the complement of 22 is 78, because 100 – 22 = 78.

How to Use this Tool:

  • Ideally use a desktop browser to make input easier.
  • Select the group of flashcards to study from the drop-down menu.
  • Type the answer as fast as possible when the question appears, and hit [Enter] or the “Go!” button.
  • The tool will check your answer and reveal your time.
  • Hit [Enter] or “Go!” again to move to the next question.
  • The tool will keep asking questions until the total time for all questions is over 30 seconds. Then it will display some statistics.



Further Notes

  • You can see improvement in just 5 minutes per day of focused practice.
  • The “study recommendations” are your incorrect answers and your slowest answers. Make a note of any of these that you need to study and commit to memory. Ignore any that were simply typos.
  • Keep a track of your performance—just like an athlete would—to see improvements and plateaus. The “correct answers” statistic is the key metric to track.
  • These tools are currently in beta mode and and available to students working with Daniel Timms. For enquiries about coaching or the other tools, use the contact details here.