LarissaMath

LarissaMath helps memorizing basic mathematical operations. It will also help to speed up solving linear, quadratic, and cubic equations with an unknown variable.
The Memory part comes from the Nobel Prize Winner in Economics Daniel Kahneman. He described the exercises in this app in his bestseller "Thinking, Fast and Slow".
It has three modes:
1. Expressions. In easy level you need to calculate multiplication, division, summation, and subtraction where at least two arguments are no greater than 10. Some examples are: 5x3=15, 25:5=5, etc. The medium level also has calculations, but now at least two arguments are no greater than 25. Some examples are: 13x13=169, 225:15=15, etc. The advanced level has more advanced expressions using numbers up to 30.
2. Equations. In easy level you have to solve a linear equation on x. For, example, -2x + 15 = 11 (solution: x = 2). This equation should ideally be solved without pen and paper. Other equations in this level are fractions, e.g. x/10 = 9/6 or 4/x = 20/5, etc. The medium level has quadratic equations and the advanced level has cubic equations.
3. Memory. Here you can see a number with between 4 and 7 digits (depending on the level) and between 0.7 and 4 seconds (this is configurable in settings). The default time is 2 seconds, as suggested by Kahneman. You have to memorize it and then type a new number, having each digit increased by one. Nine gets converted to zero. For example, if the original number is 720983, the answer will be 831094.
Additionally, the app remembers your best score and time for each mode, level, and for each number of entries.