Nth Digit
A medium-tier problem at 36% community acceptance, tagged with Math, Binary Search. Reported in interviews at Accenture and 0 others.
Nth Digit is a medium-difficulty math problem that shows up in Accenture assessments. The acceptance rate sits at 35%, which means most candidates either misread the pattern or brute-force it into a timeout. You're given a sequence of digits formed by concatenating positive integers (1234567891011121314...) and asked to find the digit at a specific position. The trick is that you can't actually build the sequence. If you hit this in a live OA and blank on the math, StealthCoder solves it invisibly while you stay composed.
Companies that ask "Nth Digit"
Nth Digit is the kind of problem that decides whether you pass. StealthCoder reads the problem on screen and surfaces a working solution in under 2 seconds. Invisible to screen share. The proctor sees nothing. Built because the OA filter rejects engineers who'd pass the on-site. That's a broken filter. This is the workaround.
Get StealthCoderThe problem requires binary search paired with mathematical properties of digit sequences. Candidates usually fail by trying to construct the string or using naive indexing. The actual approach: determine which number contains your target digit, then figure out which digit within that number. You need formulas for how many digits are used by 1-digit numbers (9 total), 2-digit numbers (180 total), 3-digit numbers (2700 total), and so on. Binary search narrows down the number range, then modular arithmetic extracts the exact digit. Most solutions that timeout attempted string concatenation or recursion without the mathematical foundation. Binary search keeps it logarithmic. If you haven't seen this pattern before and the OA timer is ticking, StealthCoder surfaces a working solution in seconds.
Pattern tags
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Make sure you actually pass it.
Nth Digit recycles across companies for a reason. It's medium-tier, and most candidates blank under the timer. StealthCoder is the hedge: an AI overlay invisible during screen share. It reads the problem and surfaces a working solution in under 2 seconds. Built because the OA filter rejects engineers who'd pass the on-site. That's a broken filter. This is the workaround. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Nth Digit interview FAQ
Why does brute force fail on Nth Digit?+
The digit position n can be very large (up to 2 billion). Building the actual concatenated string explodes memory and time. You must compute which number and which digit within that number mathematically, using logarithmic binary search and digit-count formulas.
What's the key insight for solving this?+
Break it into steps: count how many digits are used by numbers of each length (9 one-digit, 90 two-digit, 900 three-digit numbers). Binary search to find which number holds your target digit, then extract the specific digit using modular arithmetic.
Is Nth Digit still asked at companies like Accenture?+
Yes. Accenture has reported it as part of their technical assessments. It's not asked as frequently as array or string problems, but it shows up often enough that hitting it unprepared is a real risk.
How does binary search apply here?+
You binary search on the number itself, not the digit position. For each candidate number, calculate how many total digits are used up to that number. Narrow down the range until you find the exact number containing your target digit.
What's the relationship between Math and Binary Search topics?+
Math gives you the formulas to count digits efficiently. Binary search lets you find the target in log time instead of iterating through billions of numbers. Together they solve an otherwise impossible brute-force problem.
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