Stage 2 of the Rapid Mathematics track: seven trials that turn place value into real calculation — front-end adding and subtracting, compensation, and the fast checks that catch an error before it costs you. No paper.
Each trial is locked until you clear the one before it. Every level scores out of 1000 — 600 for accuracy, 400 for speed — so speed alone can't clear the bar; you have to solve most problems, and quickly. Reach 650 to unlock the next.
You can add and subtract left to right, round-and-adjust the awkward ones, and catch a wrong answer by its size, its last digit, or its parity — without reaching for paper.