Two years of outsourcing, due back in 108 seconds
Calculators are barred. So are slide rules, log tables and watches that can compute. And yet Numerical Ability is one of the six named areas. So somewhere in that exam you will multiply two numbers in your head, under a clock, having not done it unaided since roughly Class 9. That gap is real, it is entirely closeable, and almost nobody closes it because the fix feels too childish to schedule.
Decompose. Never attack head-on.
The single technique that matters. Under pressure candidates try to do a multiplication in one move, lose track halfway, and start again — burning forty seconds and their nerve.
Split it instead. 47 x 6 is not a thing you compute; it is (40 x 6) + (7 x 6) = 240 + 42 = 282. Every step is trivial and you never hold more than two numbers at once. That is the whole point: working memory is the constraint, not arithmetic.
Same for awkward decimals. 4.5 x 3 becomes (4 x 3) + (0.5 x 3) = 12 + 1.5 = 13.5. Same for percentages: 18% of 250 is 10% (25) + 5% (12.5) + 2.5% (6.25)... or far better, notice that 18% of 250 equals 250% of 18, which is 2.5 x 18 = 45. Swapping the numbers round is free and often collapses the problem entirely.
Decomposition is not a trick for people who are bad at maths. It is what people who are fast at maths actually do.
Round first, correct after
The second habit, and it pairs with the first.
Faced with 98 x 7, do not compute 98 x 7. Compute 100 x 7 = 700, then subtract the 2 x 7 = 14 you over-counted: 686. Two easy steps instead of one hard one.
This generalises. Anything near a round number should be treated as the round number plus a correction. 49, 99, 199, 0.98 — all of them are easier as neighbours of something clean.
And it has a second payoff that matters more under a clock: the rounded answer alone often decides the question. If the options are 340, 686, 1200 and 4500, then 100 x 7 = 700 has already told you the answer without any correction at all. On a multiple-choice paper, an estimate that separates the options is the answer. Precision beyond that point is time you are spending for nothing.
It is a physical skill, so treat it like one
The reason this section is short is that there is not much to know. There is a great deal to do.
Mental arithmetic behaves like a physical skill. It does not respond to understanding — you already understand it — it responds to reps. Ten minutes a day for two months will make you visibly faster. Ten hours in the last week will make you tired.
So the honest instruction is unglamorous: do sums, daily, in your head, without paper where you can manage it. Add the prices in a shop. Work out the bill before the waiter does. Halve and double things. It costs no study time because it uses time you were not studying in.
And it compounds with everything else in Part B, because arithmetic that costs you nothing frees the whole 108 seconds for the actual thinking. A candidate who is slow at sums is not just losing numerical marks — they are losing time on every question that touches a number.
The rules behind this
Sourced to the official brochure rather than restated here, so there is one place to correct when the Council revises it.
No instruments are permitted — no compass, no set squares — and no calculators, phones, or wet media.
Appendix-II states "Don't bring any instruments". Also barred: Bluetooth devices, slide rules, log tables, electronic watches with calculators, and any textual material. Numerical Ability is examined without a calculator.
Source · verified 2026-07-16
Part B examines six named areas: Visual Reasoning, Logical Derivation, General Knowledge/Architecture and Design, Language Interpretation, Design Sensitivity and Thinking, and Numerical Ability.
Visual Reasoning — understanding and reconstructing 2D and 3D composition. Logical Derivation — decoding a situation or context and drawing conclusions. General Knowledge, Architecture and Design — current issues, important buildings, historical progression, innovation in materials and construction. Language Interpretation — meaning of words and sentences, English grammar. Design Sensitivity and Thinking — observing and analysing people, space, product, environment; semantics, metaphor, problem identification. Numerical Ability — basic mathematics and its association with creative thinking; unfolding space using geometry.
Source · verified 2026-07-16
Part B allows 108 seconds per question, presented one after another, on an adaptive engine.
90 minutes across 50 questions. The adaptive structure dates to NATA 2025 per the President's foreword in V2.0, which states that NATA 2026 continues it.
Source · verified 2026-07-16
What almost everyone believes
“I am fine at maths, so mental arithmetic is not worth practising — it is beneath me.”
Being good at maths and being fast at unaided arithmetic are different skills, and you have spent two years training only the first.
Every candidate has outsourced arithmetic to a calculator since roughly Class 9, so the unaided speed has quietly atrophied while the understanding stayed intact. The exam bars calculators and runs at 108 seconds. Slow arithmetic does not only cost numerical marks — it eats the clock on every question that touches a number, which is why this drill compounds across all of Part B. It feels too childish to schedule, which is precisely why it stays undone.
Depending on how long you have
Foundation
Understand the skill. Months out, or starting from zero.
Start today and it will be free by August. Ten minutes daily, no calculator, no paper. This is the single highest-return-per-minute activity in the whole course, and it is boring, which is exactly why almost nobody does it and why doing it is an advantage.
Drill
The practice protocol. What to repeat, how often, how to score it.
Calculator banned in every session, without exception — including when you are checking your answers, because that is where it creeps back. Practise decomposition out loud until it is automatic rather than a technique you remember to use. Time individual sums; that number falling is the whole measure.
Exam-Day
What to actually do under the constraint — 108 seconds, no instruments, one pass.
Decompose everything. Round first and correct only if the options force you to. If a rounded estimate already separates the options, you are done — stop calculating and commit. Precision past the point of decision is time stolen from the next question.
Try it
Ten minutes. No calculator, no paper, and no looking anything up.
- 01Time yourself on ten of these, in your head: 47 x 6, 98 x 7, 18% of 250, 4.5 x 3, 250 / 8, 12 x 15, 999 x 4, 35% of 80, 7.5 x 12, 144 / 9.
- 02Write your total time down. That number is your baseline and it will be worse than you expect.
- 03Now redo them using decomposition and round-then-correct out loud, deliberately.
- 04Time it again. Most people are noticeably faster on the second pass, having learned nothing new — only having stopped attacking head-on.
- 05Do ten a day for a month. Compare to your baseline. This is the least interesting and most reliable advice on the site.
The short version
Calculators are barred and Numerical Ability is examined, so unaided arithmetic is due back after two years of outsourcing. Decompose rather than attacking head-on — working memory is the constraint, not arithmetic. Round first and correct after, and stop the moment the estimate separates the options, because precision past the point of decision is stolen time. It is a physical skill: ten minutes a day beats ten hours in the last week, and it frees the clock on every question that touches a number.
Next: unfolding space with geometry — the bulletin's own phrase, and very nearly a description of a net.
Questions people actually ask
- Can I use a calculator in NATA?
- No. Calculators are explicitly barred, along with slide rules, log tables and electronic watches with calculator functions — while Numerical Ability remains one of the six named Part B areas. You will do arithmetic in your head under a 108-second clock.
- What is the fastest way to multiply in my head?
- Decompose rather than attacking head-on: 47 x 6 is (40 x 6) + (7 x 6) = 282. Never hold more than two numbers at once, because working memory is the real constraint. For anything near a round number, round first and correct after: 98 x 7 is 700 minus 14.
- How precise do my calculations need to be?
- Only precise enough to separate the options. If the choices are far apart, a rounded estimate has already answered the question and further precision is time stolen from the next one. On a multiple-choice paper an estimate that discriminates is the answer.