Sum Multiples of Three, Five, or Seven

Last updated: July 27, 2026

Quick Overview

This question asks the candidate to write a function that calculates the sum of all multiples of three, five, or seven up to a given number.

Upstart
Coding & Algorithms
Software Engineer
Upstart
July 27, 2026
Software Engineer
Online Assessment
Coding & Algorithms
Medium

11

0

79 solved


This question asks the candidate to write a function that calculates the sum of all multiples of three, five, or seven up to a given number.

This question is typically asked during the online assessment round for software engineering candidates at Upstart. The interviewer is evaluating the candidate's problem-solving skills, coding ability, and understanding of basic algorithmic principles. It tests the candidate's ability to write efficient code and handle edge cases while demonstrating a clear thought process.

What the Interviewer Expects
  • Clearly define the problem and outline the approach.
  • Implement a solution using efficient algorithms.
  • Handle edge cases, such as negative numbers or zero.
  • Explain the time and space complexity of the solution.
  • Provide a clean and readable code structure with comments.
Key Topics to Cover
Basic arithmetic
Control structures
Looping
Modulus operator
Time complexity
How to Approach This
  1. Clarify input constraints and edge cases before writing code.
  2. Walk through your approach verbally and confirm with the interviewer before coding.
  3. Start with a brute force solution, then optimize. Mention time and space complexity.
  4. Test your solution with examples, including edge cases like empty input or duplicates.
  5. Consider common patterns: sliding window, two pointers, hash map, BFS/DFS, dynamic programming.
Possible Follow-up Questions
  • How would you optimize your solution for larger numbers?
  • Can you explain how you would handle negative inputs?
  • What would you change if the multiples were not limited to three, five, or seven?
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Practice DSA Problems
Sample Answer
Approach

To solve the problem, we will iterate through all numbers from 1 to the given limit and check if each number is a multiple of three, five, or seven. If it is, we will add it to a cumulative sum....

Algorithm

Here is the Python code that implements the above approach:

def sum_multiples(limit): total_sum = 0 for num in range(1, limit): if num % 3 == 0 or num % 5 == 0 or num % 7 ==...

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