Introduction
Arithmetical Reasoning combines basic maths (ages, ratios, simple arithmetic, time-distance) with logical setup. SSC Stenographer asks 2 to 3 such items per paper. They are scoring because the maths involved is class 7-8 level — the trick is forming the right equation from the word problem. After this lesson you will know the recurring question types and a step-by-step setup method.
Core Concept
Use the 4-step word-to-equation method:
1. Underline what is asked.
2. Assign one variable to the unknown closest to the answer.
3. Translate every sentence into an equation linking that variable.
4. Solve and verify by plugging back into the original story.
For age problems the formula (present age) ± n = (age n years ago/hence) handles every variant. For ratios, multiply each part by a common multiplier k. For coin problems, set up a value-per-coin × number-of-coins equation. Real-life analogy: think of the problem as a recipe — the variable is the missing ingredient, each sentence tells you a measurement.
Formula Sheet
| Type | Setup |
|---|---|
| Age (present, past, future) | Let A = present age; (A−n) = past, (A+n) = future |
| Sum of ages | (A1+A2+...+An) given as one equation |
| Ratio split | Parts in ratio a:b → ak and bk; total = (a+b)k |
| Average | Avg = Sum / Count |
| Coins | Total value = Σ (denomination × count) |
Solved Examples
Example 1. Father is 4 times as old as his son. After 5 years, he will be 3 times as old. Find their present ages.
- Let son's present age = x. Father = 4x.
- After 5 yrs: 4x + 5 = 3 (x + 5).
- 4x + 5 = 3x + 15 → x = 10.
- Son = 10, Father = 40.
- Verify: 45 = 3 × 15 ✓.
- Answer: Son 10, Father 40.
Example 2. Sum of three consecutive odd numbers is 75. Find the largest.
- Let smallest = x. Numbers: x, x+2, x+4.
- x + (x+2) + (x+4) = 75 → 3x = 69 → x = 23.
- Largest = 27.
- Answer: 27.
Shortcut: for "consecutive numbers sum" set the middle number = sum/count.
Question Patterns
- Age problems — present, past, future ratios.
- Ratio division — split a quantity in given ratio.
- Number of coins / notes — value-and-count equations.
- Average puzzles — adding/removing items affects average.
- Distance & time word problems — speed × time = distance.
- Logical sequence missing-number — hybrid of pattern and arithmetic.
Mistakes to Avoid
1. Setting the variable to the wrong unknown. Always assign the variable to what's directly asked.
2. Forgetting to add the time shift on both sides. "After 5 years" affects every age in the equation.
3. Mishandling ratios. Use a multiplier k; do not assume a:b means a units literally.
4. Skipping verification. A 5-second back-substitution catches arithmetic slips.
Exam Importance
| Exam | Frequency | Marks | Notes |
|---|---|---|---|
| SSC Stenographer | High | 2–3 | Age and ratio dominate |
| SSC CGL | High | 3–5 | Mixed types |
| RRB NTPC | High | 3–4 | Average and ratio common |
Why Arithmetical Reasoning is high-yield. SSC Stenographer 2026 asks 2–3 arithmetical-reasoning items every paper. Standard sub-types: ages (present-future-past relationships), ratio and proportion, percentage word problems, profit and loss, simple and compound interest, time-speed-distance, time-and-work, averages, mixtures and allegations. Build a one-page formula sheet. Ages: if A is currently x and B is y, then after t years their ages become x+t and y+t — set up the relation as an equation. Ratio: convert words to ratios first ("twice as old as" means 2:1; "5 years more" means add 5). Percentage: x% of y = xy/100; if a value increases by p% then decreases by p%, the net change = −p²/100. Profit/Loss: SP = CP × (1 + P%/100); discount on MP. SI = PRT/100; CI = P(1+r/100)ⁿ − P. TSD: speed = distance/time; relative speed for opposite direction = sum, same direction = difference. Time-Work: if A does work in x days, A's 1-day work = 1/x; combined work LCM method. Practise 10 arithmetical reasoning questions daily for 6 weeks. Cap each question at 50 seconds.
Quick Revision
- Underline what is asked first.
- Use one variable for the closest unknown.
- Apply time-shift on both sides for age problems.
- Use multiplier k for every ratio.
- Coin problems: value × count.
- Verify by back-substitution.
- Aim 60 seconds per question.
- Solve 10 PYQ word problems daily.
- Age problems: 'A is twice as old as B' → A = 2B; 'X years ago' → (A−X) = relation × (B−X).
- Ratio problems: A:B = 3:5 → A = 3k, B = 5k; sum/difference gives k directly.
- Mixture problems: 'replace x litres of milk with water' → use ratio formula M(1−x/M)ⁿ.
- Average problems: change in average × number = total change in sum.
- Profit/loss in word form: SP = CP × (100 ± profit%)/100 — always check the percentage base.
- Drill 100 SSC PYQ arithmetical-reasoning items to lock the recurring set-ups.