# Letter combinations from a phone keypad digit string Aced (formerly Exponent) publishes a public search API over its indexed pages; the guide is at https://www.aced.io/agents/agent-access. Source: https://www.aced.io/questions/6359/generate-letter-combinations-phone-keypad Source observed: 2026-11-04T23:46:11.006Z Last checked: 2026-11-04T23:46:11.006+00:00 Indexed: 2026-11-06T16:46:30.722+00:00 --- # Letter combinations from a phone keypad digit string We publish this coding interview question for candidates preparing for software engineering interviews. Given a string containing digits from **2 through 9** and the classic phone-keypad mapping, return every possible letter combination represented by the number. ## Question details - **Category:** [Data Structures & Algorithms](https://www.aced.io/questions?type=algorithms) - **Also tagged:** [Coding](https://www.aced.io/questions?type=coding) - **Role:** [Software Engineer](https://www.aced.io/questions?role=swe) - **Company:** [Amazon](https://www.aced.io/questions?company=amazon) - **Reported last asked:** 9 months ago Detailed company statistics for this question require an upgrade: [Upgrade](https://www.aced.io/upgrade?src=questions). ## Interview experience One interview experience is associated with this question: [Amazon · 9 months ago](https://www.aced.io/experiences/amazon-software-engineer-interview-39a0db) > I interviewed for an SDE II role, and the whole process felt pretty standard and transparent. Amazon told me upfront what the process would look like, so I did not feel like I was guessing what came next: first an online assessment, then three 40-minute interviews back to back on the same day. The technical questions were all very classic problems, and the biggest surprise was that my interviewers often started with coding first instead of spending the first part on behavioral. The behavioral side was still important, but the follow-ups went deep into the actual details of my work instead of stopping at a polished STAR answer. After the loop, my recruiter mostly asked about logistics like start date and work authorization, and then they sent me the offer letter. > > — Software Engineer · Mid Level / L4 ## Community answers No answers have been contributed by the community yet. Sign in or create an account to submit an answer. ## Related questions - [Count total possible combinations of N-digit numbers in a mobile keypad.](https://www.aced.io/questions/1174/total-combinations-n-digit-numbers-mobile-keypad) - [Given two strings (Word 1 and Word 2) and a list of valid words from a dictionary, return the minimum number of operations required to convert Word 1 to Word 2.](https://www.aced.io/questions/1980/minimum-operations-convert-string) - [Given two strings, return true if you could change 2 letters in the s string and return the goal string. If this isn't possible, return false.](https://www.aced.io/questions/4344/buddy-strings) ## Related courses ### [Software Engineering Interview Prep](https://www.aced.io/courses/software-engineering) ![Software Engineering Interview Prep](https://images.ctfassets.net/x78yjrjc11pq/4VkuYewBHUFIVUS5oJDW5h/02e833439b1289f25f38f13f81cbdca3/adobe_stock_optimized.jpeg?w=800&h=800&fm=webp&q=75) We help candidates prepare for software engineering roles at Google, Amazon, Microsoft, Meta, Apple, and other top companies with mock interviews, frameworks, and advice from senior candidates. 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