H9A
Count any digit in any range — instantly.
What it does
H9A counts how many times a digit (0–9) appears across any range of numbers. Unlike brute-force scripts, it uses a closed-form O(log n) algorithm, so a range from 1 to 1,000,000,000,000 returns instantly. It prints a colorized, step-by-step breakdown of each decimal place, supports machine-readable JSON, and can render terminal-style screenshots.
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