What's the best way to master Digit Sum Sorting Input-Output Problems quickly?

Master Digit Sum Sorting Input-Output Problems by understanding the core concepts first, practicing regularly with our worksheets, and applying the shortcut techniques provided.

Digit Sum Sorting Medium

Digit Sum Sorting problems present a sequence of numbers as input. Numbers are sorted based on the sum of their digits (e.g., 23 → 2+3=5), with ties broken by the number's value. These problems test your ability to calculate digit sums and apply multi-criteria sorting rules.

10Worksheets

200+Practice Questions

MediumDifficulty

2-3 hoursHours to Master

What You'll Learn

Introduction & Overview Why This Matters How to Solve Pro Tips & Tricks

Shortcut Methods Common Mistakes Practice Worksheets Exam Importance

Introduction to Digit Sum Sorting Medium

Prerequisites

Digit sum calculation Numerical sorting concepts Multi-criteria sorting Basic arithmetic

Why This Matters: Digit Sum Sorting problems appear in 1-2 questions in Banking PO and SSC CGL exams. They test digit manipulation and sorting skills.

How to Solve Digit Sum Sorting Medium Problems

Step 1: Calculate the digit sum for each number

Step 2: Sort numbers primarily by digit sum (ascending)

Step 3: For numbers with equal digit sums, sort by the number value (ascending)

Step 4: The final output is the sorted sequence

Step 5: Verify digit sums and order for all numbers

Pro Strategy: Calculate digit sum for each number. Group numbers by their digit sum. Within each group, sort by the actual number value. Concatenate groups in ascending order of digit sums.

Example Problem

Example: Input: '15 42 28 91 56' Digit sums: 15→6, 42→6, 28→10, 91→10, 56→11 Sorted by digit sum: 6,6,10,10,11 Within digit sum 6: 15 then 42 (15<42) Within digit sum 10: 28 then 91 (28<91) Final: '15 42 28 91 56' Answer: 15 42 28 91 56

Pro Tips & Tricks

Digit sum = sum of all digits in the number
Example: 123 → 1+2+3 = 6
For two-digit numbers: tens digit + units digit
For three-digit numbers: hundreds + tens + units
Numbers with smaller digit sums come first
If digit sums are equal, the smaller number comes first

Shortcut Methods to Solve Faster

Final output = sorted(numbers, key=lambda x: (sum(int(d) for d in str(x)), x))

Calculate all digit sums first, then sort

Create pairs (digit_sum, number) and sort by both

Numbers with same digit sum appear in numerical order

Common Mistakes to Avoid

Miscalculating digit sum (forgetting to add all digits)

Sorting by number value only, ignoring digit sum

Sorting by digit sum only, ignoring tie-breaking rule

Treating digit sum as digital root (reducing to single digit - not needed here)

Practice Worksheets

Practice makes perfect! Work through these worksheets to master Digit Sum Sorting Medium. Each worksheet contains 20 questions with detailed explanations. Start from Worksheet 1 and progress through increasing difficulty levels.

Worksheet 1 Beginner Beginner level - Perfect for building foundational understanding

Worksheet 2 Beginner Beginner level - Perfect for building foundational understanding

Worksheet 3 Beginner Beginner level - Perfect for building foundational understanding

Worksheet 4 Intermediate Intermediate level - Test your understanding with moderate difficulty

Worksheet 5 Intermediate Intermediate level - Test your understanding with moderate difficulty

Worksheet 6 Intermediate Intermediate level - Test your understanding with moderate difficulty

Worksheet 7 Advanced Advanced level - Challenge yourself with complex problems

Worksheet 8 Advanced Advanced level - Challenge yourself with complex problems

Worksheet 9 Advanced Advanced level - Challenge yourself with complex problems

Worksheet 10 Advanced Advanced level - Challenge yourself with complex problems