The worked question on this page is original educational practice. It is not represented as a question from an official previous-year examination paper.
01 / UNDERSTANDING
Review the question
Write original expressions with widely spaced and closely spaced options. Compare the minimum working precision needed in each version and justify why the rougher estimate stops being decisive.
02 / UNDERSTANDING
The concept in context
Rounding errors can accumulate or partially offset. If choices are close, retain more precision or compute the sensitive part exactly. Check the order of magnitude at the end: a result ten times too large often reflects a decimal or percentage mistake rather than harmless approximation. An estimate should be labelled as such when exactness is not justified.
03 / UNDERSTANDING
A worked learning case
Original educational case. The original expression 49.8 × 20.2 is near 50 × 20 = 1,000. Expanding it gives 1,005.96, so 1,000 is a useful rough estimate. If candidate answers were 900, 1,000 and 1,100, this may be sufficient; if they were 1,005 and 1,006, the same rough calculation would not settle the choice.
ORIGINAL EDUCATIONAL PRACTICE
Try it before you check.
Original practice: Estimate 19.9 × 5.1 to the nearest ten.
Show the answer and reasoning
100.
The exact product is 101.49, which rounds to 100 to the nearest ten. Using the nearby values 20 and 5 also suggests 100. The prompt’s precision matters: that estimate is suitable for tens, but it would not be an exact answer or the nearest-integer result, which would be 101.
Two traps to watch for.
- Rounding aggressively when answer choices are very close.
- Ignoring operation order because the expression is approximate.
YOUR TOPIC-SPECIFIC LEARNING MAP
Learn from the attempt
Predict the scale of the answer.
Choose rounding precision from the required accuracy.
Compare the estimate with one exact check.
Explain the idea, apply it to a new situation, then check what changed in your reasoning.
BANKERS TUTORIAL · SOURCE NOTES
Keep the source alongside your notes.
Official links provide subject context and authoritative reference material. This guide’s explanation, scenario and question are original Bankers Tutorial learning content.
- sbi.bank.in https://sbi.bank.in/web/careers/current-openings
- sbi.bank.in https://sbi.bank.in/webfiles/uploads/files_2627/09/SBI_JA-Customer_Support_Sales-IH_Pre-2026-27_Eng.pdf
For SBI preparation, check the current official notice before relying on changing dates, rules or examination requirements.
