Took me a moment to understand the rules (especially that decimal places are invalid), and the controls are a little unwieldy for quick input, but once I got the hang of it I found it a fun challenge that did require some strategy. The visuals are very stylish too.
I liked that if I had an equation in progress I wouldn't score when the time ran past, and sometimes found myself trying to divide or subtract to chase the timer rather than increase to meet it.