What is 5% of 400000?

Introduction / Context:
This question tests your ability to quickly compute a simple percentage of a large number. Although the number 400000 looks big, the calculation is straightforward once you remember how to interpret percentages. Such quick mental calculations are very helpful in competitive exams and day to day financial decisions.

Given Data / Assumptions:

We need to find 5% of 400000.

We interpret 400000 as four lakh in the Indian numbering system.

Concept / Approach:
The standard formula for percentage is:
x% of N = (x / 100) * N.
Here x = 5 and N = 400000. Simplifying 5 / 100 gives 1 / 20, which makes the multiplication with 400000 very easy to handle. This method avoids dealing with long decimals and keeps the calculation clear and exact.

Step-by-Step Solution:
Step 1: Express 5% as a fraction: 5% = 5 / 100.Step 2: Simplify 5 / 100 = 1 / 20.Step 3: Compute (1 / 20) of 400000.400000 / 20 = 400000 / (2 * 10) = 200000 / 10 = 20000.Step 4: Therefore, 5% of 400000 = 20000.

Verification / Alternative check:
Alternatively, convert 5% to decimal: 5% = 0.05. Then multiply: 0.05 * 400000 = 5 * 400000 / 100 = 2000000 / 100 = 20000. This matches the earlier computation, confirming the correctness of the result.

Why Other Options Are Wrong:
4000 is only 1% of 400000, not 5%.
16000 and 8000 are arbitrary smaller values that do not match 5% of 400000.
10000 corresponds to 2.5% of 400000, which is half of the required percentage.

Common Pitfalls:
Some candidates mistakenly move the decimal point incorrectly or misinterpret 5% as 0.5 instead of 0.05. Others divide by 5 instead of multiplying by 5 / 100. To avoid such errors, always carefully convert percentage to fraction or decimal first and then perform the multiplication using simple steps or factorization tricks like cancelling zeros and dividing systematically.

Final Answer:
5% of 400000 is 20000.