Tabular DI — Study Notes
Overview
Unlike complex DI formats, tabular DI presents data in rows and columns, making extraction straightforward — the real test is your calculation speed and accuracy under time pressure.
In SBI Clerk Prelims, you typically encounter tables showing production figures, sales data, population statistics, or employee counts across different years, companies, or categories. Questions demand direct calculations: finding totals, averages, percentages, ratios, and percentage changes. Since Prelims is about speed (you have roughly 20 minutes for 35 quant questions), mastering quick mental math with tables gives you an edge.
This topic connects directly with percentage, ratio, and average concepts. Students who practice tabular DI also strengthen their overall calculation ability, which helps across the entire Numerical Ability section.
Key Concepts
- Data Extraction First: Before touching your pen, spend 10–15 seconds understanding what the rows and columns represent. Misreading headers is the #1 source of errors.
- Row vs Column Totals: Questions often ask for totals across a row (one entity, multiple time periods) or down a column (multiple entities, one time period). Know which direction you're summing.
- Percentage Calculation: Most questions boil down to (Part/Whole) × 100. Identify what's the "part" and what's the "whole" from context.
- Percentage Change Formula: Always uses the base (earlier/original) value in the denominator. Direction matters — increase vs decrease.
- Ratio Simplification: After extracting two values, find HCF quickly to express ratios in lowest terms. SBI often gives options like 3:4, 4:5, 5:6.
- Average Across Categories: Sum all values, divide by count. Watch out for weighted averages when quantities differ.
- Approximation is Your Friend: When numbers are large and options are spread apart, round to nearest tens or hundreds before calculating.
Formulas / Key Facts
Percentage of A out of B = (A / B) × 100
Percentage Increase = [(New – Old) / Old] × 100
Percentage Decrease = [(Old – New) / Old] × 100
Ratio of A to B = A : B (simplify by dividing both by HCF)
Average = Sum of all values / Number of values
Difference as Percentage of a Value = [(A – B) / Reference Value] × 100
Quick Fraction-to-Percentage Conversions
- 1/2 = 50%, 1/3 ≈ 33.33%, 1/4 = 25%, 1/5 = 20%
- 1/6 ≈ 16.67%, 1/7 ≈ 14.28%, 1/8 = 12.5%, 1/9 ≈ 11.11%
Worked Examples
Sample Table: Number of laptops sold by 5 companies in 3 years (in hundreds)
| Company | 2021 | 2022 | 2023 |
|---|---|---|---|
| A | 45 | 52 | 60 |
| B | 38 | 44 | 50 |
| C | 55 | 48 | 62 |
| D | 42 | 50 | 55 |
| E | 30 | 36 | 45 |
Example 1: What is the percentage increase in sales of Company E from 2021 to 2023?
Solution:
- Old value (2021) = 30
- New value (2023) = 45
- Increase = 45 – 30 = 15
- Percentage increase = (15/30) × 100 = 50%
Answer: 50%
Example 2: What is the ratio of total sales of Company A to Company B across all three years?
Solution:
- Total for A = 45 + 52 + 60 = 157
- Total for B = 38 + 44 + 50 = 132
- Ratio = 157 : 132
- Check if simplifiable: HCF of 157 and 132 = 1 (both are coprime)
Answer: 157 : 132
Example 3: Sales of Company C in 2022 are what percent less than its sales in 2023?
Solution:
- 2022 value = 48
- 2023 value = 62
- Difference = 62 – 48 = 14
- Base for "less than 2023" = 2023 value = 62
- Percentage = (14/62) × 100 = (7/31) × 100 ≈ 22.58%
Answer: Approximately 22.6%
Example 4: What is the average sales of all companies in 2022?
Solution:
- 2022 values: 52 + 44 + 48 + 50 + 36 = 230
- Number of companies = 5
- Average = 230/5 = 46 hundreds = 4600 laptops
Answer: 46 (in hundreds)
Common Mistakes
- Confusing "more than" vs "of": "A is what percent more than B" uses B as base. "A is what percent of B" also uses B as base, but no subtraction. Students swap these and get wrong answers. → Fix: "More/less than X" means X is the denominator. "Of X" also means X is the denominator.
- Misreading row/column headers: Picking 2022 data when question asks for 2023, or reading Company C row for Company D. → Fix: Underline or circle the exact cell(s) needed before calculating.
- Forgetting to convert units: Table says "in hundreds" but student calculates as if actual numbers. → Fix: Check table title and footnotes for unit multipliers.
- Using wrong base for percentage change: For "increase from X to Y," base is X (the starting point), not Y. → Fix: The word "from" indicates your base value.
- Over-calculating when approximation works: Spending 90 seconds on exact division when options are 22%, 28%, 35%, 41%. → Fix: If options differ by 5%+, approximate aggressively.
Quick Reference
- Read table headers (rows, columns, units) before any calculation.
- Percentage change = (Difference / Base) × 100; base is the "from" or "original" value.
- For ratios, always simplify to lowest terms using HCF.
- Average = Total Sum ÷ Count of items.
- When options are spread apart, approximate; when close, calculate precisely.
- "What percent of" and "what percent more/less than" both use the reference value as denominator.