# Number System and Simplification CDS PYQ Topic Wise

> Number System and Simplification CDS PYQs: all 306 questions from 66 official papers (2016–2026), by concept with official answers. Asked in 11 of 11 years.

Source: https://previousyearquestions.app/cds/topics/cds-number-system/

Explore: <a href="/cds/topics/">All CDS topics</a> · <a href="/cds/topics/elementary-mathematics/">CDS Elementary Mathematics PYQs</a> · <a href="/cds/">CDS hub</a> · <a href="/cds/syllabus-pattern/">Syllabus & pattern</a> · <a href="/cds/2026/">CDS 2026</a>

## Answer first

Number System and Simplification PYQs (previous year questions) for CDS: Number System and Simplification (Elementary Mathematics) had **306 questions** across the 66 official CDS papers we tagged (2016–2026), and appeared in 22 of them. Asked in 11 of 11 years. The concepts asked in the most papers: HCF and LCM, Remainders, Divisibility.

## Year-wise question count

<ChapterQuestions exam="cds" chapter="cds-number-system" part="trend" />

## Most-asked concepts

Sorted by the number of papers a concept appeared in.

<ChapterQuestions exam="cds" chapter="cds-number-system" part="concepts" />

## How to practise Number System and Simplification PYQs

1. Start with the concepts at the top of the table. They have come back the most.
2. Solve one year's Number System and Simplification questions from the official PDF against the clock, then check the answer listed below.
3. Log every miss as a concept gap, a calculation slip or a misread. Each needs a different fix.
4. Once a concept is clean in two papers, move to the next. Then sit a full paper from the year pages.

## Questions by year

Each line gives the question number and paper, type, concept, our one-line summary and the official answer, with a link to the official PDF.

<ChapterQuestions exam="cds" chapter="cds-number-system" part="questions" />

## Other Elementary Mathematics topics

- [Percentage, Ratio, Profit and Interest PYQs](/cds/topics/cds-arithmetic/)
- [Time, Speed and Work PYQs](/cds/topics/cds-time-speed-work/)
- [Algebra PYQs](/cds/topics/cds-algebra/)
- [Trigonometry PYQs](/cds/topics/cds-trigonometry/)
- [Geometry PYQs](/cds/topics/cds-geometry/)
- [Mensuration PYQs](/cds/topics/cds-mensuration/)
- [Statistics PYQs](/cds/topics/cds-statistics/)

## FAQ

### How many Number System and Simplification questions come in CDS?
In the official papers we tagged: 21 in 2026, 34 in 2025, 44 in 2024, 28 in 2023, 17 in 2022, 22 in 2021, 29 in 2020, 34 in 2019, 22 in 2018, 23 in 2017 and 32 in 2016 (2 papers each year). That is 306 questions in all, about 14% of Elementary Mathematics.

### Which Number System and Simplification topics repeat in CDS?
Asked in the most papers: HCF and LCM, Remainders, Divisibility. The concept table lists every one with its count.

### Are these official CDS questions?
Yes. Every question is from an official CDS paper hosted on our year pages. The one-line summaries are ours; open the PDF linked beside each question for the full text.