Power of Three
A easy-tier problem at 48% community acceptance, tagged with Math, Recursion. Reported in interviews at Goldman Sachs and 0 others.
Power of Three is an easy problem that looks deceptively simple: determine if an integer is a power of three. Goldman Sachs has asked it. The acceptance rate sits at 48 percent, which means almost half the candidates who attempt it don't pass. That gap usually signals a trap: the obvious brute-force loop works fine, but interviewers probe for the mathematical insight that separates candidates who memorized patterns from those who actually understand the math. If you hit this during your assessment and blank on the trick, StealthCoder surfaces a working solution in seconds, invisible to the proctor.
Companies that ask "Power of Three"
Power of Three 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. Made by a working Amazon engineer who got tired of watching qualified friends bomb OAs they'd solve cold in an IDE.
Get StealthCoderThe brute-force approach divides by 3 repeatedly until you either land on 1 (it's a power) or hit a number that doesn't divide evenly (it's not). That passes, but the interviewer expects you to know the math shortcut: powers of three have a fixed set within integer bounds. For a 32-bit signed integer, the largest power of three is 1162261467. If your number divides that evenly with no remainder, it's a power of three. This avoids loops entirely and screams mathematical literacy. Recursion is listed as a topic, so be ready to defend a recursive divide-by-3 approach too, even though iteration is cleaner. The real pitfall is overthinking edge cases like 1 (which is 3 to the power of 0) and negative numbers (not powers of three by definition). StealthCoder handles all edge cases and surfaces both the modulo shortcut and the recursive variant so you can pick the one your interviewer respects.
Pattern tags
You know the problem.
Make sure you actually pass it.
Power of Three recycles across companies for a reason. It's easy-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. Made by a working Amazon engineer who got tired of watching qualified friends bomb OAs they'd solve cold in an IDE. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Power of Three interview FAQ
Is Power of Three really an easy problem?+
The acceptance rate is 48 percent, so technically yes, but the gap suggests candidates solve it the brute-force way and miss the mathematical trick. If your interviewer digs deeper and asks why your approach is optimal, you need the modulo insight. That's where the 'easy' label breaks.
Does Goldman Sachs actually ask this?+
Yes, it's reported in their interview data. It's a low-volume ask, but if it appears on your assessment, you're prepped. The fact it's easy-tier and a single company asks it suggests it's a screening filter for mathematical thinking, not a core interview problem.
What's the trick most candidates miss?+
The optimal solution uses modulo arithmetic: the largest power of three in 32-bit range is 1162261467. If your number divides it evenly, it's a power of three. Most candidates loop and divide, which works but shows you don't know the math. The modulo trick is O(1) and screams you understand the domain.
Does recursion matter for this problem?+
Recursion is listed as a topic, so your interviewer might ask for it. A recursive divide-by-3 approach is clean but not optimal. Have both ready: iteration with the modulo trick is faster, but recursion shows you can think functionally if they push for it.
What are the edge cases?+
Test 1 (which is 3 to the power of 0), 0, and negative numbers. Negative numbers are not powers of three by definition. These trips up candidates who code too fast. The modulo approach handles them naturally if you bound-check correctly.
Want the actual problem statement? View "Power of Three" on LeetCode →