Worksheet generator

1.B — 3 centsKA-0010Money and change

• AI found the smallest amount that cannot be made rather than the largest one.
• CI did not notice that 7 is 2 plus 5, so I marked it as impossible without testing it.
• DI only tried using coins of one kind at a time and never mixed the two denominations.
• EI assumed odd amounts are impossible because one of the coins is even.

2.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.

3.C — 55 degreesKA-0022Angles on lines, in triangles, in polygons

• AI assumed the triangle was isosceles because it had a right angle, so I repeated the 35.
• BI assumed a right-angled triangle always has two 45 degree angles.
• DI subtracted 35 from 100 instead of from 90, mixing the angle sum up with a round number.
• EI subtracted only the 35 from 180 and forgot to take off the right angle as well.

4.E — 60KA-0026Percentages and simple discounts

• AI worked out the size of the discount and gave that as the new price instead of subtracting it.
• BI treated a quarter off as half off and took the price down to 40.
• CI applied the 25% reduction twice, taking 80 down to 60 and then 60 down to 45.
• DI subtracted 25 euros rather than 25 percent, treating the percentage as an amount of money.

5.C — 110KA-0029Unit conversion

• AI subtracted correctly in metres but then gave the answer in metres when centimetres were asked for.
• BI converted 3.5 metres to 35 centimetres instead of 350.
• DI subtracted without converting at all, taking 3.5 away from 240.
• EI added the two lengths instead of finding the difference between them.

6.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.

7.C — 9:36KA-0041Factors, multiples, LCM and GCD by listing

• AI found the greatest common divisor of 12 and 18 instead of the least common multiple.
• BI added the two intervals together rather than looking for a time that is a multiple of both.
• DI found a common multiple but not the least one, landing on a later coincidence.
• EI multiplied the two intervals together instead of finding their least common multiple.

8.C — 16KA-0050Working backwards

• AI added the 4 and the 6 and stopped, forgetting to undo the halving.
• BI doubled the 6 first and then added the 4, reversing the steps in the wrong order.
• DI doubled the total at the end rather than doubling only the amount left after the first spend.
• EI doubled twice because spending half felt like it needed undoing more than once.

9.C — 14KA-0051Complementary counting

• AI counted the multiples of 3 and gave that instead of the numbers that are not multiples.
• BI counted 21 as a multiple of 3 inside the range, so I removed one too many.
• DI removed only the multiples of 3 that are also even, so I subtracted three instead of six.
• EI gave the size of the whole range and forgot to remove anything at all.

10.C — 210KA-0057Clever regrouping (pair to round numbers)

• AI paired the numbers from the outside in but left the 20 out of every pair, so I added only up to 19.
• BI estimated the total as a round number instead of working it out.
• DI used eleven pairs of 20 instead of ten pairs of 21.
• EI multiplied 20 by 21 and forgot that pairing counts every number twice.

11.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.

12.C — 5KA-0061Operation puzzles and cryptarithms

• AI solved for the triangle and gave that instead of the square.
• BI found the triangle is 4 and gave that number, without going on to the second equation.
• DI halved the 12 instead of dividing it by the three triangles.
• EI subtracted the wrong way round, taking 9 from a number instead of taking the triangle from 9.

13.E — the two diagonals are the same lengthKA-0079Properties of triangles and quadrilaterals

• AI confused a rectangle with a square, which is only one special kind of rectangle.
• BI remembered a fact about squares and rhombuses and applied it to every rectangle.
• CI counted the two diagonals as lines of symmetry, which only works for a square.
• DI used the angle sum of a triangle on a four-sided shape.

14.B — 24KA-0083Perimeter and area of rectilinear shapes

• AI subtracted 6 from 20 and gave that, which is neither a side nor an area.
• CI took the other side to be 20 minus 6 divided by 2, forgetting there are two sides of each length.
• DI multiplied the perimeter by half the known side instead of finding the missing side first.
• EI used 16 as the other side, taking 20 minus 6 plus 2 rather than working from the perimeter properly.

15.C — 12KA-0086Tiling and tessellation

• AI divided the floor area by 3 instead of by the tile area of 2.
• BI laid tiles along the edges only and never filled the middle.
• DI gave the area of the floor rather than the number of tiles that cover it.
• EI multiplied the floor area by the tile area instead of dividing.

16.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.

17.A — blackKA-0108Repeating cycles and position mod n

• BI got a remainder of 1 but read the last colour of the repeat rather than the first.
• CI thought the pattern had no fixed first tile, even though tile one is given.
• DI assumed a repeating pattern must eventually change.
• EI assumed the pattern runs only for as many tiles as one repeat contains.

18.B — 8KA-0119Find what is actually being asked

• AI halved the difference, as if the question asked how many Bo should hand over to make them equal.
• CI gave how many Bo has now rather than how many more he has than Ana.
• DI gave the number Bo started with, without doing anything.
• EI added the two amounts together instead of comparing them.

19.C — 4KA-0120Draw the diagram

• AI assumed the walk was a loop because the north and south distances match.
• BI gave one of the distances walked rather than the distance from the start.
• DI added the two different directions together instead of drawing where the cat ends up.
• EI added up the whole distance walked, which is not the same as the distance from the start.

20.C — 2/5KA-0141Number lines and betweenness

• AI compared the bottom numbers and assumed a bigger denominator means a bigger fraction.
• BI saw that 4 lies between 3 and 2 and assumed one quarter therefore lies between the two fractions.
• DI checked that it is bigger than one third but never checked it against one half.
• EI compared the top numbers only and ignored what the bottoms do to the size.

21.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.

22.E — 8KA-0143Systematic listing

• AI counted the two available digits rather than the numbers they can build.
• BI counted the three positions instead of the numbers.
• CI used only two of the three positions when multiplying.
• DI multiplied 2 by 3, mixing the number of digits with the number of positions.

23.A — 8KA-0144Translating a sentence into an equation

• BI subtracted 8 from 19 rather than working the two steps backwards.
• CI subtracted the 3 from 19 and gave that without halving it.
• DI added the 3 to 19 instead of subtracting it.
• EI doubled 19 and added 3, applying the machine forwards instead of undoing it.

24.E — (7, 3)KA-0145Grid coordinates and lattice reasoning

• AI moved left instead of right, subtracting the 4 rather than adding it.
• BI moved left and up, reversing both directions.
• CI swapped the two coordinates round before moving.
• DI moved up instead of down, adding the 2 rather than subtracting it.

25.C — 100 degreesKA-0152Angles on lines, in triangles, in polygons

• AI found the smaller of the two unknown angles and stopped before doubling it.
• BI split the remaining 150 degrees into two equal halves instead of a one-to-two split.
• DI split the remainder evenly into 75 and 75, then doubled one of them.
• EI assumed that the largest angle in a triangle like this must be a right angle.

26.B — 76.80 poundsKA-0153Percentages and simple discounts

• AI assumed a 20 percent rise and a 20 percent fall must cancel because the percentages match.
• CI applied only the fall and forgot the rise.
• DI got the size of the change right but the direction wrong.
• EI applied only the rise and forgot the fall.

27.C — 4KA-0161Remainders and modular cycles

• AI assumed the cycle ends on 1 at every exponent that is a multiple of 2.
• BI used a remainder of 1 rather than 2 when dividing 50 by 3.
• DI doubled my way to 2 cubed = 8 and used 8 minus 2.
• EI assumed a large power of 2 must eventually be divisible by 7.

28.A — 1KA-0169Remainders and modular cycles

• BI reduced 7 to 2 correctly but then used a remainder of 1 when dividing 100 by 4.
• CI read the cycle backwards and landed on the entry before the right one.
• DI used 100 divided by 4 giving 25 and read off the 25th entry as if the cycle had length 25.
• EI assumed a power that large must be divisible by 5.

29.A — 150 degreesKA-0170Angles on lines, in triangles, in polygons

• BI found the exterior angle and answered with that instead of the interior one.
• CI used 360 divided by 12 subtracted from 195, or otherwise slipped a step in the arithmetic.
• DI gave the total of all twelve interior angles rather than one of them.
• EI used a ten-sided polygon by mistake.

30.A — 33KA-0171Recursive rules

• BI used the rule 2a(n) - 1 but started the sequence at 1 instead of 2.
• CI doubled six times and ignored the minus one entirely.
• DI stopped at a(5), one term early.
• EI computed 2^6 - 1, applying the minus one only once at the very end.