Odisha Police Sub‑Inspector (SI) – Quantitative Aptitude
Topic: Tables
Tables are pre‑calculated lists of numbers that help you solve problems quickly without performing long calculations.
In the SI exam you will encounter questions that can be answered by looking up a value in a table or by cross‑referencing two tables (e.g., multiplication × division, factor × divisor).
1. Simple Explanation
| Table | What it shows | Typical use in questions |
|---|---|---|
| Multiplication Table (1‑10 or 1‑12) | Product of two numbers | “What is 7 × 8?”; “Find 9 × 7.” |
| Division Table | Quotient of two numbers | “What is 56 ÷ 8?”; “Find 120 ÷ 6.” |
| Factor Table (for numbers 1‑100) | Factors of a given number | “List all divisors of 48.” |
| Powers Table | Powers of 2, 3, 5, 10 etc. | “What is 2⁵?”; “Compute 3⁴.” |
| Multiples Table | Multiples of a base number up to a limit | “How many multiples of 7 are ≤ 100?” |
| Consecutive Sum Table | Sum of first n natural numbers | “Sum of 1 to 50.” |
| LCM/GCD Table | LCM/GCD of two numbers | “LCM of 12 and 18.” |
Why tables are useful
- Speed – A quick glance replaces a multi‑step calculation.
- Accuracy – Eliminates arithmetic errors.
- Memory aid – Repeated exposure embeds the patterns in your mind.
2. Key Points
| # | Point | Why it matters for SI exam |
|---|---|---|
| 1 | Remember 1–10 multiplication table | 60 % of SI aptitude questions rely on these. |
| 2 | Know the division table for 1–10 | Division questions often ask for quotients or remainders. |
| 3 | Have a factor table for 1–100 | Enables quick factorisation, LCM/GCD, and divisor‑count questions. |
| 4 | Powers of 2, 3, 5, 10 | Exponential problems (e.g., growth, compound interest) appear frequently. |
| 5 | Multiples table up to 100 | Useful for “how many” or “next multiple” problems. |
| 6 | Sum of first n natural numbers | Provided as a quick reference: S = n(n+1)/2. |
| 7 | LCM/GCD for common pairs | Memorise LCM of 3, 4, 6, 8, 12; GCD of 12 & 18, 15 & 20, etc. |
| 8 | Use “cross‑reference” technique | Example: to find 9 × 8, look at 9 in multiplication table and 8 in row/column. |
| 9 | Avoid mental math for large numbers | Stick to tables; mental arithmetic can lead to mistakes. |
| 10 | Practice with sample problems | Repetition reinforces pattern recognition. |
3. Worked Example
Problem
A candidate is to arrange the numbers 12, 18, 24, 30, 36 in ascending order and then find the product of the first and last numbers. Use tables for a quick solution.
Solution
-
Sort the numbers
All numbers are multiples of 6.
Use the Multiples Table of 6 (up to 40):6×1 6×2 6×3 6×4 6×5 6×6 6×7 6×8 6×9 6×10 6 12 18 24 30 36 42 48 54 60 From the table, the ascending order is:
12, 18, 24, 30, 36
-
Product of first and last numbers
- First number = 12
- Last number = 36
Use the Multiplication Table (1–12) or cross‑reference:
12 36 12 144 432 36 432 1296 → 12 × 36 = 432
Answer
The product of the first and last numbers is 432.
Why tables helped
- The multiples table instantly gave the sorted list.