Nice and original, but the writing of the fractions was a bit off.
maybe have a selector you can adjust the whole numbers, numerator, and denominator with +/- buttons?
Could also go with more levels.
Level 1 could be for multiples of 1/2, level 2 for multiples of 1/3, level 3 for 1/4s, etc.

And after level 99: the boss round converts to decimals from X/100.

It is pretty good, it made my brain think, good job!

How dare you make me think and learn! Good game, a few spelling errors here and there but not enough to distract from the point of the game.

Since the clock ticks down as the user tries to meet the written criteria ("1, 1/4") I'd suggest maybe for future ones a timed multiple choice.