Bank Written Math Masterclass: How to Solve Problems Step-by-Step (No Shortcuts)

Bank Job Written Math: Stop using MCQ shortcuts! Learn the correct step-by-step format for Bank Job Written Math exams. Covers Profit/Loss, Time & Work, and Interest with solved examples for 2026.

In the Preliminary (MCQ) stage of a bank job exam, the goal is speed. But in the Written Exam, the goal is logic and process. A common mistake candidates make is using “shortcut techniques” (like the Rule of 100 or Magic Fraction) in the written answer script. This often results in receiving zero marks even if the final answer is correct.

Examiners at BIBM, Arts Faculty (DU), or Private Banks want to see how you derived the answer. They are testing your analytical depth, not just your calculation speed.

Here is the definitive guide on how to structure and solve written math problems for the 2026 bank exam season.

The 3 Golden Rules of Written Math

Rule 1: No Shortcuts Allowed

• Wrong: $CP = \frac{SP \times 100}{120}$ (Direct shortcut formula)
• Right: “Let the Cost Price be $x$. According to the question, $x + 20\% \text{ of } x = SP$…”

Rule 2: Define Your Variables

Always start by declaring what your unknown variables represent.

• Example: “Let the total number of students be $x$.” or “Let the speed of the train be $s$ km/hr.”

Rule 3: Use Standard Connectors

Use phrases to guide the examiner through your logic:

• “According to the question (ATQ)…”
• “We know that…”
• “Therefore…”
• “Hence…”

Topic-Wise Solved Examples (Standard Format)

Here are the correct step-by-step methods for the three most common written topics:

1. Profit & Loss (Most Common)

Question: A shopkeeper sells a watch at a 10% profit. If he had bought it at 10% less and sold it for Tk. 20 less, he would have gained 20%. Find the Cost Price.

Correct Written Solution:

Let the original Cost Price (CP) of the watch be Tk. $100x$.

Case 1 (Original Scenario):

Profit = $10\%$

Selling Price (SP1) = $100x + 10\% \text{ of } 100x = 110x$

Case 2 (New Scenario):

New Cost Price = $100x – 10\% \text{ of } 100x = 90x$

New Profit = $20\%$

New Selling Price (SP2) = $90x + 20\% \text{ of } 90x$

$= 90x + 18x$

$= 108x$

According to the question (ATQ):

$SP1 – SP2 = 20$

$\Rightarrow 110x – 108x = 20$

$\Rightarrow 2x = 20$

$\Rightarrow x = 10$

$\therefore$ The original Cost Price $= 100x = 100 \times 10 = 1,000$ Tk.

Answer: Tk. 1,000

2. Time & Work (The “Unitary Method”)

Question: A can do a piece of work in 10 days and B in 15 days. They work together for 5 days, and then B leaves. How many days will A take to finish the remaining work?

Correct Written Solution:

Work done by A in 1 day $= \frac{1}{10}$ part.

Work done by B in 1 day $= \frac{1}{15}$ part.

Combined work of (A + B) in 1 day:

$= \frac{1}{10} + \frac{1}{15}$

$= \frac{3 + 2}{30}$

$= \frac{5}{30} = \frac{1}{6}$ part.

Work done by (A + B) in 5 days:

$= \frac{1}{6} \times 5 = \frac{5}{6}$ part.

Remaining work $= 1 – \frac{5}{6} = \frac{1}{6}$ part.

Now, A completes $\frac{1}{10}$ part in 1 day.

$\therefore$ A completes 1 (full) part in 10 days.

$\therefore$ A completes $\frac{1}{6}$ part in $10 \times \frac{1}{6} = \frac{5}{3}$ days.

$= 1.67$ days (approx) or $1\frac{2}{3}$ days.

Answer: $1\frac{2}{3}$ days.

3. Interest (Simple vs. Compound)

Question: What is the difference between Simple Interest (SI) and Compound Interest (CI) on Tk. 5000 for 2 years at 10% per annum?

Correct Written Solution:

Given,

Principal $(P) = 5000$ Tk.

Rate $(r) = 10\% = 0.10$

Time $(n) = 2$ years

Step 1: Calculate Simple Interest (SI)

We know, $SI = P \times n \times r$

$= 5000 \times 2 \times 0.10$

$= 1000$ Tk.

Step 2: Calculate Compound Interest (CI)

We know, Amount $(A) = P(1+r)^n$

$= 5000 (1 + 0.10)^2$

$= 5000 (1.1)^2$

$= 5000 \times 1.21$

$= 6050$ Tk.

$\therefore CI = A – P = 6050 – 5000 = 1050$ Tk.

Step 3: Calculate Difference

Difference $= CI – SI$

$= 1050 – 1000$

$= 50$ Tk.

Answer: Tk. 50

5 Pro-Tips for Presentation

1. Box Your Answer: Always put a rectangular box around your final answer. This makes it easy for the examiner to spot amidst the calculations.

2. Rough Work: Do calculations (multiplication/division) on the right margin or the last page of your script. Do not clutter the main body.

3. Don’t Skip Steps: Even if the calculation is obvious (e.g., $100 – 20 = 80$), write it down.

4. Language Consistency: Private banks (like DBBL, MTBL, EBL) usually require solutions in English. Govt. Banks often allow Bangla, but writing Math in English is safer and more standard.

5. Clean Corrections: If you make a mistake, draw a single line through it. Do not scribble or overwrite.

Resource Recommendation:

For practicing written math specifically, refer to:

• Khairul’s Advanced Math (Written Part)

• Professor’s Math Review (Written Section)

• Mentors’ Math Q-Bank (For Private Bank patterns)