Great visual aesthetics. I love the use of minimal shapes and colors combined with movement. This made me realize how frequently I'm off by 1 when doing mental math.
One thing I would've appreciated is some memory of where I was placing the triangles before I inevitably failed and had to restart on some of the trickier puzzles. I was organizing the game space with clusters of triangles that formed plausible combinations. I thoroughly enjoyed doing that combination using the provided game space, and that process would've been made even more enjoyable if the triangles remained in the locations I positioned them too across tries. Just a small quality of life upgrade -- it did not significantly detract from an overall enjoyable experience :)