Truncated Division
💡Chop both the top and bottom to their first two or three significant digits, then divide. How many digits you keep depends on how close the options are.
Try it — estimate a fraction
liveKeep the first two significant digits, then divide.
- 1
Truncate both to two significant digits
4,873 → 4,800, 61,200 → 61,000
- 2
Divide the trimmed numbers
4,800 / 61,000 ≈ 0.08
- 3
As a percentage
≈ 7.87% (exact 7.96%)
⏱️ Practice against the clock
A worked example
4,873 / 61,200 ≈ 49 / 612 ≈ 8%. Keeping two digits is enough here because the answer choices are not tightly packed.
Chop the tail, do not round
Rounding nudges a number to its nearest neighbour. Truncating just lops off the trailing digits, which is faster and, for sizing up a fraction, plenty accurate. 4,873 / 61,200 becomes 49 / 612, roughly 8%.
The ratio barely budges, because you trimmed the top and bottom the same way. Whatever you dropped was pulling in the same direction on both numbers.
Two digits, sometimes three
Two significant digits handle most of these. Reach for a third only when two answer choices sit within a few percent of each other and that last digit is what tells them apart.
This is the real speed skill on timed quant sections: match your effort to how far apart the options are, and quit the second the estimate is decisive.
Questions people ask
How is this different from ordinary rounding? ▾
Rounding nudges to a nearby value; truncating simply drops the trailing digits. Truncating is faster and, for sizing a fraction, usually accurate enough.
When do I need to keep three digits instead of two? ▾
When two of the answer choices are within a few percent of each other. Tighter options demand one more digit of precision.