The short answer
Section III gives you numbers but rarely rewards long arithmetic — how to get the right one without doing the sum.
Written and checked by GAMSAT tutors — not AI-generated.
Try the reasoning style
We treat forgetting as a failure — a lapse to be patched with reminders and records. Yet a mind that kept everything could not think; it would drown in the undifferentiated noise of every moment it had ever lived. To forget is not so much to lose information as to decide, mostly without our noticing, what was never worth keeping.
The author's argument relies most directly on which unstated assumption?
Pick an option to see how the tutor reasons to the answer — not just whether you were right.
Not quite — the answer is B.
Work backwards from the conclusion: a mind that ‘kept everything’ supposedly ‘could not think.’ That only follows if thinking means leaving most of experience out — so B is the premise the argument quietly rests on. A raises reliability, which the passage never weighs; C contradicts ‘mostly without our noticing’; D smuggles in a claim about intellect the passage never makes. The question rewards finding the hidden premise, not recalling a fact.
Section III hands you numbers constantly, and almost never rewards grinding through them. The options are usually spread far enough apart that a one-significant-figure estimate picks the answer outright. The marks are in setting the calculation up — knowing what to multiply by what — not in the arithmetic that follows.
The trap is doing it properly
Full arithmetic costs you a minute you don't have and buys accuracy the options don't need. If the choices are 5, 10, 20 and 40, working to three decimal places is wasted effort — you only ever needed to know which power of ten you were in.
Four steps, in this order
Say what the answer looks like
Before touching a number: what units must it come out in, and roughly how big should it be? An answer in the wrong units is wrong however neat the arithmetic, and this step catches it in advance.
Round hard
To one significant figure. 72 becomes 70, 0.048 becomes 0.05, 9.81 becomes 10. You are aiming at the right option, not the right decimal.
Split the digits from the zeros
Do the small numbers in your head and the powers of ten separately: is "3 over 3, then one power of ten left" — that is 10, and you never wrote anything down.
Check the options, then refine
If one option is close and the rest are miles away, you are finished. Only when two sit near your estimate is it worth going back and doing it exactly.
Which mode the question wants
Estimate
- The options differ by a factor of two or more
- The stem says "approximately", "roughly" or "of the order of"
- You are choosing between orders of magnitude
- The numbers are ugly — ugly numbers are a hint that precision is not the point
Calculate
- Two options sit within about 20% of each other
- The stem asks for a value to a stated precision
- The whole question turns on a small difference between two large numbers
- You already have the setup and the arithmetic is one step
Worked example — estimate, then check
A drug is infused at 4.0 mg per kilogram per hour into a 72 kg patient. The bag holds 3.0 g. Roughly how long before it runs out?
Check yourself
A tank fills at 250 mL per minute. Roughly how long to fill 6.0 L?
Most of these are proportions, not sums
A large share of quantitative stems never ask for a value at all — they ask what happens to one quantity when another changes. "The radius doubles; what happens to the area?" needs no numbers, only , so the area goes up four times. Find the relationship and the arithmetic usually disappears. Watch the power: doubling something that sits under a square is a factor of 4, under a cube a factor of 8, and under a square root only about 1.4.
Check yourself
A reaction's rate doubles for every 10 °C rise in temperature. Going from 20 °C to 50 °C, the rate increases by a factor of:
Check yourself
A spherical cell's radius triples. Its surface-area-to-volume ratio changes by a factor of:
Key takeaways
- Decide the units before you touch a number — they tell you what to multiply and what to divide.
- Round to one significant figure, and do the digits and the powers of ten separately.
- Stop as soon as one option is clearly closest; only refine when two are close.
- If the stem describes a change rather than a value, look for the proportion — squares give 4×, cubes 8×, square roots about 1.4×.
Practise this with real GAMSAT-style questions
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