Know other facts (2)

Work out what else you know if you know one fact.

Create my FREE account

including a 7 day free trial of everything

Email Address

Password

Newsletter

The URBrainy email newsletter (sent every 2 weeks) provides resource updates and helpful guides for teaching and learning.

Yes, I would like to receive the URBrainy newsletter.

I agree to the Terms and Conditions and Privacy Policy

Already have an account? Sign in

Important concepts on the relationship between addition and subtraction.

It's amazing how much you really know, if you just think about it!

Check answers are correct by working them out in a different order.

Finding pairs of numbers that add up to 50.

The latest news, articles, and resources, sent to your inbox weekly.

URBrainy named one of the World’s Top EdTech Companies by TIME Magazine.