Who needs math skills? Or at least, that's what every schoolchild in the country asks themselves whenever they sit down to solve a quadratic equation or perform trigonometry.

Sadly, we all need math skills. Although high-level calculus might be a bit beyond everyday requirements, the ability to perform fast mental arithmetic, work out percentages, and understand basic equations is useful in the supermarket, the office, and while doing your latest home-improvement project.

Unfortunately, the Organisation for Economic Co-operation and Development (OECD) says that nearly one in three adults in the United States scores below Level 2 in numeracy, leaving them as the third-worst performer in the block (ahead of Italy and Spain).

If you're not a strong mathematician, or if you want to brush up on your skills, read on to find out the best Math Games for Android:

Countdown Maths Game [No Longer Available]

UK readers will be very familiar with the concept, with the game being based off a popular TV show that's run since 1982.

The game will give you a random three figure total and six smaller numbers which you must use to make the total. You can only use each number once and can only use addition, subtraction, multiplication, and division.

There are a range of difficulties, starting at the very easy and going all the way up to "Mental". The game also includes a two player mode to introduce another layer of fun.

Playing this game for a few weeks will quickly sharpen up your arithmetic skills.

2Vars

2Vars is another game to get your mental arithmetic moving in the right direction.

Short for "Two Variables", the game gives you one number in a simple-looking equation, and you have to fill in the two blanks from the options provided.

2vars-android

The equations start simple and get progressively more difficult as you move up through the levels. From a "learning math" standpoint, the beauty of the game is that it will force you to do several sums for each right answer, especially as the problems become more challenging.

Advanced long multiplication and long division equations are slowly introduced, and the location of the blank spaces within the equation changes with each question.

Finally, there's a leaderboard and a series of unlockable achievements that will give you a sense of progression.

Simply Sudoku

The Sudoku craze might have died down somewhat, but that doesn't mean it's not an excellent game to play if you want to improve your math ability.

For those that don't know, the game traces its roots back to the Belle Époque era in France, though the modern game was developed in the USA in the late 1970s.

Given its explosion in popularity in the middle of the last decade, it is no surprise that there are hundreds of Sudoku games in the Play Store. Nonetheless, Simply Sudoku is arguably the best.

As with almost all Sudoku games, there are different difficulty levels, hints, a pencil mode, and an array of fancy graphics. However, it also offers some unique features -- namely a smart keyboard that shows the potential answers in an empty square, and long-pressing the pencil tool, which will fill all the empty squares with their possible solutions.

Algebra Tutor [No Longer Available]

If you're already strong with basic arithmetic, perhaps you're ready for something (much) more challenging: learning complex algebra.

algebra-tutor

Do you know how to evaluate single variable linear expressions? Or how to name polynomials by their number of terms? Perhaps you'd like to learn about how to convert expanded forms to exponent forms?!

Algebra tutor certainly isn't for the faint hearted, but if you're serious about learning something new, it's a great option. It'll let you practice 35 different algebraic forms and offers step-by-step solutions so that you can see where you made any mistakes. It'll also track your performance across all the different types of problems, meaning that once you've used the app for a while you can easily highlight your strong and weak points.

Math Effect [No Longer Available]

Math Effect is the reverse of the earlier-mentioned Countdown game. You are presented with an equation and a solution, and you only have to decide whether the solution is right or wrong. It sounds easy, but the whole game is timed, meaning balancing accuracy and efficiency is no easy task. If you make one error, it's game over.

There are multiple game modes, including a time mode, a fixed equation mode, and an unlimited mode, and there's also a highly-detailed statistics page that monitors how accurate you are and how fast you are, alongside a host of other metrics.

Threes!

Possibly the most well-known on the list, Threes! is one of those games that takes Android owners by storm.

The premise is simple: one game mode, one difficult level, and one aim -- to get the multiples-of-three-score as high as possible before the 4x4 grid gets filled up.

You do this by shifting the grid to add numbers together, but as soon as you shift the board, a new number gets introduced.

Sounds complicated? It shouldn't be, but it is frustrating and rewarding in equal measure. Watch the video below for a demonstration.

Your Recommendations?

What mental math games do you recommend? Have you found an undiscovered gem? Or perhaps you've stumbled across another game that helps develop an area of mathematical skill that we didn't touch on?

Let us know your tips and recommendation (and your highest score on Threes!) in the comments below.