-Four four different Domino, No matter which side you pick, within seconds you could calculate the total sum of any four lines of numbers.
-This is a magical mathematical trick toy, you can use it to cultivate children’s passion for learning mathematics.
-You can even give a calculator to the audience, and challenge them to a match. See who will get the calculation done faster, and more accurately! All props can be checked!
– Kingmagic Brand , High Quality