A number matrix links each row by one rule: your child finds it, checks every row and fills the gap. Your child is tested at their current year level, and each school selects its own test date.
Edutest lists matrices among the kinds of Numerical Reasoning question. In our questions a matrix is a small grid of numbers: every row, or every pair, follows the same rule, and one number is missing.
First
Second
Third
2
5
9
4
1
9
6
3
?
Here the rule is "double the first number and add the second". Twice 2 plus 5 makes 9, and twice 4 plus 1 makes 9 again. So the gap is twice 6 plus 3, which is 15.
The rule runs across each row, not down a column, so the habit to build is reading across first.
Try simple rules on one full row, then test the winner on every other row. A rule that fits only one row picks a wrong option.
Read across, not down
The rule links the numbers in a row. A pattern down a column is a distraction to set aside.
Try simple rules on the first complete row
Add, take away and multiply first, then mixed rules such as double one number and add the other.
Check the rule on every other complete row
If it fails on any row, drop it and try the next.
Fill the gap, working backwards if needed
If the missing number sits in the middle, undo the rule. If 27 take away the gap is 20, the gap is 7.
Put the answer back in
The finished row should obey the rule like the others.
Which rules should your child try first?
These are the rules our matrix questions use, from one step to two. Try them in this order, simplest first, so no time goes on a hard rule when an easy one fits.
Two-step rules take longest, and trying a few before one fits is part of the method.
Common matrix rules
Rule
A row that fits
Why it is tricky
Multiply, then add
5 → 16 (times 3, add 1)
The answers can look like a series of their own
Double one, add the other
5, 2 → 12
Doubling the wrong number fits some rows, not all
Multiply the two, then adjust
3, 4 → 10 (3 × 4 − 2)
Two steps, so one row never settles it
Three times one, take away the other
6, 5 → 13
The answer can be smaller than a number in the row
Add the two, then square
1, 2 → 9
Grows fast, so it looks like multiplying
Why are fractions and factors on this page?
They ask what a matrix asks: how is one number built from another? We call this group number relations, and each answer comes from seeing a link, not from a long sum.
Fractions and decimals. To find the fraction closest to a decimal, turn each option into a decimal and compare the gaps. Knowing that 2/3 is about 0.667 and 3/4 is 0.75 makes this quick.
A number from a clue. "Five times a number is 36 more than twice it" is about the difference: three lots of the number make 36, so the number is 12.
Factors and squares. A square number has every prime factor in pairs. So a square that divides by 2 and by 3 must divide by 36, the product of a pair of 2s and a pair of 3s.
Four worked examples
We wrote these in the style of the Edutest test: a pair rule first, then fractions, a clue and factors. Each one shows the answer and the working. Read them with your child and talk through why the right option is right.
For each one, ask your child to say the rule in their own words, then check it together against every row or condition. That check is what turns a guess into an answer.
Worked explanation 1
In each pair, the second number is made from the first number by the same rule. What number replaces the question mark?
First number
Second number
4
13
7
22
10
31
12
?
AA.
40
BB.
37
CC.
36
DD.
25
Answer: B
Answer: B (37)
Look across each row, not down the column. Multiply the first number by 3 and add 1: 4 × 3 + 1 = 13, 7 × 3 + 1 = 22, 10 × 3 + 1 = 31. So 12 × 3 + 1 = 37.
The trap: 40 tempts children who see the second column going up by 9 and carry on, missing that the first column jumps by only 2 at the end.
Why the other options are wrong
A (40): Continues the second column's +9 pattern, ignoring the first number.
C (36): Multiplies by 3 but forgets to add 1.
D (25): Doubles and adds 1, which gives 9 for the first pair, not 13.
Worked explanation 2
Which fraction is closest to 0.7?
AA.
5/7
BB.
2/3
CC.
3/4
DD.
7/9
Answer: A
Answer: A (5/7)
Change each fraction to a decimal. 5/7 ≈ 0.714, 2/3 ≈ 0.667, 3/4 = 0.75 and 7/9 ≈ 0.778. The gaps from 0.7 are about 0.014, 0.033, 0.05 and 0.078, so 5/7 is closest.
The trap: 2/3 tempts children who know 2/3 is about 0.67 and stop there without checking 5/7, which is even closer.
Why the other options are wrong
B (2/3): About 0.667, which is 0.033 away.
C (3/4): Exactly 0.75, which is 0.05 away.
D (7/9): About 0.778, the furthest away.
Worked explanation 3
When a number is multiplied by 6, the answer is 84 more than when the same number is multiplied by 2. What is the number?
AA.
14
BB.
42
CC.
21
DD.
28
Answer: C
Answer: C (21)
Six lots of the number is 4 lots more than two lots of it. So 4 lots of the number make 84, and the number is 84 ÷ 4 = 21. Check: 6 × 21 = 126 and 2 × 21 = 42, and 126 − 42 = 84.
The trap: 14 tempts children who divide 84 by 6 straight away instead of thinking about the difference between 6 lots and 2 lots.
Why the other options are wrong
A (14): Divides 84 by 6.
B (42): Divides 84 by 2.
D (28): Divides 84 by 3, as if the difference were 3 lots.
Worked explanation 4
What is the smallest square number that divides exactly by 2, 3, 4, 5 and 6?
AA.
3600
BB.
400
CC.
360
DD.
900
Answer: D
Answer: D (900)
The smallest number that divides by 2, 3, 4, 5 and 6 is 60, so the answer must be a multiple of 60. A square needs every factor in pairs: 60 = 2 × 2 × 3 × 5, so it needs another 3 and another 5. 60 × 3 × 5 = 900 = 30 × 30, and 900 ÷ 4, 900 ÷ 6 and the others all divide exactly.
The trap: 400 tempts children who look for a square that ends in 00 and forget to check that it divides by 3.
Why the other options are wrong
A (3600): Is a square that works (60 × 60), but 900 is smaller.
B (400): Is a square, but 400 ÷ 3 does not divide exactly.
C (360): Divides by all of them but is not a square number.
Which number facts make these faster?
The ones your child knows without working out. Calculators are not allowed in the test room. So each fact here saves a written sum:
the times tables up to twelve twelves, and the division facts that go with them;
square numbers up to 225, and cube numbers up to 125;
the decimals for halves, quarters, fifths, thirds and eighths;
quick tests for dividing by 3 and 9 (add the digits), by 4 (the last two digits) and by 6 (even and divisible by 3);
the smallest number that several small numbers all divide into.
Each trap below matches a wrong option in the examples. Name the slip with your child, then use its check on the next few questions.
Following a column. In the pair-rule example, the second numbers rise by 9 at first, but the first numbers don't rise evenly, so carrying on down the column misses.
Stopping at the familiar fraction. The fraction your child knows well isn't always the closest. Convert every option before choosing.
Dividing by the wrong number. In a "more than" clue, divide by the difference between the multipliers, not by the larger one.
Checking one condition. A square ending in 00 can still fail to divide by 3. Test every divisor in the question.
A rule that fits one row. It stays a guess until every complete row agrees.
How can your child practise number matrices?
Play "what's my rule" at home. One person says a number and what it turns into, and the guesser names the rule after three goes. Then try rules where a pair makes a third, just as a matrix row does.
In the app, the number relations lesson has an Interactive version and Notes. There are also drills by section and topic; a free account drills the free test's questions, and a paid plan opens the rest. Rules that build a list rather than a row are on the number series page.
Four questions show the method; the Numerical Reasoning section of Practice test 1 shows whether your child can use it against the clock. Afterwards, results by skill show whether matrices are costing marks. For grids that run as rows of three, see the Numerical Reasoning sample questions.
