This self-working card trick uses a simple number principle to reveal a selected card in a surprising way. With minimal ...

This self-working card trick looks completely impossible at first. Even after a fair shuffle, simple counting and basic math ...

Rǒta counts things. That’s it, really — what a cheap little mechanical counter does with a thumb press, or what you can do by counting on your fingers and toes, that’s pretty much all that Rǒta does.

Your child is learning new things every day. And just as you can help them with their language and reading, there are also ways you can boost your preschooler’s number skills. This is especially ...