How quick can you count up or down?

That's the challenge posed by CalQ, a recently released and free mobile game about combining tiles of numbers to reach a target integer. Think somewhere along the lines of Spelltower, only mathematical.

CalQ is board-based, complete with rows and columns of numbered tiles that can either be positive, negative, or a multiplier.

Swiping across the grid horizontally or vertically combines these cells, effectively creating a kind of "equation" as you attempt to reach a designated number.

For example, if the number is 5, you could navigate the board to combine +2, +2, -3, +1, x2, and +1. Sometimes, the answer will be simpler, like 3+2, but going the longer route has a greater payoff. The more tiles eliminated during an equation, the more points you can earn.

Incorporating the rare gold star tile multiplies your score without adding anything to the equation, an extra encouragement to extend your route to the target number.

The different game modes include Normal mode, played in 90 second rounds, and Time Attack mode, where eliminating numbers adds more time to the initial 90 seconds.

You can test your mental math skills with CalQ on both iOS and Android.