Tap the Arrow Buttons on the left to move and tap the Arrow Button on the right to jump. Look at the equation in the upper left corner before moving. Once you're ready, you have ten seconds to find the missing number for each equation!

Once you get the equation right, you can grab the key to unlock the door. Make sure you don't run into the spiky enemies!

HINT: When you have multiple equations, you have to grab the numbers to solve the top equation and then work your way down.