Worksheet generator

1.D — ThursdayKA-0021Remainders and modular cycles

• AI found the remainder 2 but counted the two days starting from today rather than starting from tomorrow.
• BI divided 100 by 7 and used the quotient of 14, treating the leftover days as if there were none.
• CI remembered there was a remainder but used a remainder of 1 instead of working it out.
• EI counted 100 divided by 7 as 14 remainder 3 instead of remainder 2.

2.B — 28KA-0035Handshakes and pairs

• AI doubled the number of people, as if each person made two handshakes in total.
• CI let each person shake hands with all eight people including themselves before halving.
• DI multiplied 8 by 7 and forgot that each handshake was counted from both sides.
• EI multiplied 8 by 8, counting every ordered pair including a person with themselves.

3.D — 4320KA-0059Estimation and order of magnitude

• AI worked out the drips in an hour and stopped there.
• BI multiplied by the 24 hours but forgot the 60 minutes in each one.
• CI used 6 hours in a day, thinking of waking hours rather than a whole day.
• EI used 600 minutes in an hour rather than 60.

4.B — 7KA-0064Fractions of a quantity

• AI divided 28 by 7 instead of taking a quarter of it.
• CI found three quarters of 16 by mistake, mixing up the class size.
• DI found how many did travel by bus and gave that instead of how many did not.
• EI subtracted the 4 quarters as if they were 4 students.

5.B — 75KA-0088Angles on lines, in triangles, in polygons

• AI added the three angles wrongly, getting 295 instead of 285.
• CI used an angle sum of 370, mis-remembering the total for a quadrilateral.
• DI repeated one of the given angles instead of computing the missing one.
• EI used the triangle's 180 degrees and then adjusted, rather than the quadrilateral's 360.

6.E — 86400KA-0124Estimate to the nearest choice

• AI gave the number of minutes in a day instead of the number of seconds.
• BI gave the number of seconds in one hour rather than in a whole day.
• CI multiplied the 24 hours by a round thousand instead of converting properly.
• DI multiplied 60 by a round thousand, using one conversion and inventing the other.

7.C — HKA-0142Line and rotational symmetry

• AI found the vertical fold and assumed a horizontal one must work too.
• BI found the horizontal fold and stopped without testing the vertical one.
• DI counted the vertical fold twice rather than testing a horizontal one.
• EI mistook turning the letter upside down for folding it, which is rotation rather than symmetry about a line.

8.D — 15KA-0024Ratio as parts of a whole

• AI found what one part is worth and gave that as my answer instead of multiplying it back up.
• BI divided 40 by the five blue parts instead of by the eight parts that make the whole.
• CI read the ratio 3 to 5 as meaning 3 out of every 5 and worked from that.
• EI found the value of one part correctly but then multiplied by 5 instead of 3, giving the blue counters.

9.C — 61KA-0030Arithmetic sequences and the nth term

• AI added the step 18 times, counting the gaps between terms one too few.
• BI multiplied the step of 3 by 20 and forgot that the first term is already in place.
• DI used a first term of 3 instead of 4 while adding 20 steps.
• EI added the step 20 times to the first term instead of 19 times.

10.C — 9 timesKA-0042Scaling and similar figures

• AI applied the length scale factor straight to the area.
• BI doubled the scale factor because area involves two dimensions, instead of squaring it.
• DI multiplied the scale factor by four, as though area scaled with the number of sides.
• EI cubed the scale factor, which is the rule for volume rather than area.

11.B — 2 hoursKA-0044Combined work rates

• AI subtracted the two times from each other rather than adding the rates.
• CI averaged the two times, which would only be right if the taps took turns instead of running together.
• DI added the two times together, which makes the tank slower with two taps than with one.
• EI used the faster tap's time alone and ignored the contribution of the slower one.

12.D — 24KA-0073Arrangements of a few objects

• AI counted the letters rather than their arrangements.
• BI multiplied 4 by 3 and stopped, forgetting the last two positions.
• CI used 4 choices for every position, as if letters could repeat.
• EI used 4 choices in each of four positions, which allows every letter to repeat.

13.B — BoKA-0092Ordering and ranking from clues

• AI gave the child who is first rather than the one who is second.
• CI placed Cal directly after Ana, reading ahead of Dee as meaning immediately ahead.
• DI built the order backwards from the last position instead of forwards from the first.
• EI assumed the clues left several orders open without checking that they chain into a single one.

14.B — 8KA-0100Working backwards

• AI undid the operations in the order they were written instead of in reverse order.
• CI gave the final answer back, assuming the three steps cancelled each other out.
• DI doubled the 11 and subtracted the 6 but forgot the final halving that undoes the doubling.
• EI undid only the halving and stopped there without touching the other two steps.

15.C — 65KA-0103Recursive rules

• AI stopped at the fourth term, counting the starting number as the first step rather than the first term.
• BI generated one term too few, giving the fifth term instead of the sixth.
• DI doubled six times and subtracted 1 only once at the end.
• EI generated one term too many, giving the seventh instead of the sixth.

16.B — 21KA-0104Recursive rules

• AI counted the two starting terms as one, so I stopped at the seventh term.
• CI added the two before it but slipped once in the middle of the chain.
• DI generated one term too many and gave the ninth.
• EI doubled each term instead of adding the two before it.

17.C — 55KA-0107Growth patterns and figurate numbers

• AI stopped at the eighth triangle, losing count while adding the rows.
• BI gave the ninth triangle instead of the tenth, being one row short.
• DI gave the eleventh triangle, adding one row too many.
• EI squared the position number, which describes square patterns rather than triangular ones.

18.D — 1200KA-0128Check units and re-read before bubbling

• AI worked entirely in metres and gave the answer in square metres.
• BI multiplied 30 by 0.4 without converting the metres to centimetres at all.
• CI converted 0.4 m to 4 cm rather than 40 cm.
• EI converted 0.4 m to 400 cm, moving the decimal point one place too far.

19.E — 408KA-0129Sanity-check with a second method

• AI worked out 17 times 20 and forgot to add the 17 times 4 part.
• BI worked out 17 times 4 as 28 instead of 68 when adding the parts together.
• CI worked out 17 times 4 as 48 instead of 68 when adding the parts together.
• DI made a carrying slip of ten in the final addition of the two parts.

20.C — 8KA-0147Circles: radius, diameter, and touching circles

• AI subtracted the radii, which is the answer when one circle sits inside the other.
• BI averaged the two radii instead of adding them.
• DI multiplied the radii together rather than adding them.
• EI added the two diameters instead of the two radii.

21.E — No, it is impossibleKA-0028Parity arguments

• AI found a sequence that turned over most of the cups and assumed the last one could be fixed somehow.
• BI matched the number of moves to the number of cups without checking whether the target is reachable at all.
• CI assumed that with enough moves any arrangement can be reached.
• DI thought the choice of which cups to flip could change whether the target is reachable.

22.A — 8KA-0031Counting paths on a grid

• BI assumed closing one junction removes about half the routes and halved the total of 20.
• CI counted the routes that pass through the closed junction and gave that instead of the ones that avoid it.
• DI subtracted only the 2 routes that reach the closed junction, not all the routes that continue through it.
• EI counted every route on the open grid and forgot to remove the ones through the closed junction.

23.C — 4KA-0040The pigeonhole principle

• AI answered with the lucky case, where the first two socks happen to match.
• BI used the number of colours as my answer without adding one for the sock that must repeat.
• DI worked from the number of socks of each colour instead of the number of colours.
• EI took the whole drawer, guaranteeing a pair but far more socks than are needed.

24.D — 12KA-0060Operation puzzles and cryptarithms

• AI added the digits of 132 instead of working out what A and B must be.
• BI found A + B correctly and then halved it, as if the question wanted one digit.
• CI spotted the 11 in the working and gave that instead of the sum it multiplies.
• EI found a pair of digits by trial and misadded them by one.

25.C — 7KA-0077The pigeonhole principle

• AI answered with the luckiest case, where the first three balls happen to match.
• BI found the worst case of two of each colour and forgot to take one more.
• DI multiplied the three colours by the three balls I need, rather than thinking about the worst case.
• EI worked from the number of balls of each colour rather than from the number of colours.

26.C — 55KA-0078Extremal / worst-case counting

• AI found the smallest possible total of the other nine and gave that instead of what is left.
• BI assumed the biggest number could be at most half the total.
• DI made the other nine numbers all equal to 1, forgetting that they have to be different from each other.
• EI ignored the other nine numbers entirely, as if the biggest could take the whole total.

27.B — 9KA-0095The extremal principle

• AI divided 100 by 12 and rounded down instead of up.
• CI rounded the division to a convenient number without checking that a packing with a smaller maximum exists.
• DI gave the number of boxes as the answer rather than a number of apples.
• EI described the case where one box holds everything, which is possible but not guaranteed.

28.D — No, because the number of moves is oddKA-0097Parity arguments

• AI assumed enough moves can undo anything, without asking what each move preserves.
• BI tried a few sequences that nearly worked and assumed a better choice would finish the job.
• CI reached for the number of items rather than for what a single swap actually changes.
• EI thought the choice of swaps could change the outcome, when every swap has the same effect.

29.B — 11KA-0112Mixtures and weighted averages

• AI averaged the two averages, ignoring that the classes are different sizes.
• CI weighted the averages but used the wrong class size against each one.
• DI leaned towards the larger class's average without computing the totals.
• EI added the two averages together instead of combining them.

30.B — Answer it with your best guess, mark it, and move onKA-0126Time triage: now, later, or guess

• AI let the time already spent decide, but that time is gone whatever I do next.
• CI moved on but left a blank, which scores nothing if I never get back to it.
• DI spent time re-reading work I had no reason to doubt, while 21 unseen questions waited.
• EI assumed the hardest questions are the best use of time, when the unseen easy ones are worth the same each.