An estimation question asks for the closest amount, so your child rounds to friendly numbers, works mentally and checks the size. Your child is tested at their current year level, and each school selects its own test date.
It gives awkward numbers and asks which option is closest, or which is the best estimate. Your child doesn't need the exact answer, just one near enough to tell the options apart, found fast.
Edutest describes Numerical Reasoning as series, matrices, arithmetical reasoning and deduction. Estimation is arithmetical reasoning done roughly, and it pays off beyond these questions.
That's because of the rules on the day: Edutest doesn't allow calculators, rulers, dictionaries, working-out paper, mobile phones, smart watches and fitness trackers. A child who rounds well saves time on every long calculation, not just on the ones that ask for an estimate.
Round to numbers that are easy to work with, then keep track of which way each one moved. Knowing the direction is what lets your child correct the estimate when two options sit close together.
Round each number to a friendly one
3.95 becomes 4, 21 becomes 20, and 465 becomes 450 or 470, whichever divides easily.
Note which way each number moved
If both were rounded up, the true answer is a bit lower than the estimate.
Work it out mentally
Friendly numbers turn a long multiplication into a quick one.
Adjust if the options are close
Take back what the rounding added. 21 boxes at 5c less each is about a dollar less.
Choose by size
Compare the estimate with the options. The nearest one is the answer.
Why check the size of the answer?
Because some questions set options a factor of ten apart: a few thousand, tens of thousands, hundreds of thousands. Then the arithmetic hardly matters. What matters is counting the zeros and not leaving out a step.
A quick sense check catches these slips. Teach your child to ask: is this a sensible size for what it counts? A week of blinking runs into the tens of thousands; a few thousand would mean barely blinking at all.
Which units cause trouble?
Mixed units are where estimates go wrong, because a conversion done the wrong way shifts the answer a long way. Ask your child to change everything into one unit before rounding anything.
Unit changes to do first
What the question gives
Change it to
Watch for
Hours and minutes
All in minutes
Count in sixties, not hundreds
Minutes and seconds
Whole minutes, rounded, or all in seconds
Dropping the seconds changes the answer a lot
Every second day in a month
A count of days
The first and last days may both count
A price per 1000 litres
How many thousands are used
Moving the decimal point the wrong way
Cents and dollars
One unit throughout
Mixing them in a single sum
Four worked examples
We wrote these in the style of the Edutest test, from a quick rounding to a cost that takes several steps. Each one shows the answer and the working. Read them with your child and talk through why the right option is right.
Look at how the working rounds each number, and ask your child which way each one moved. A number rounded the wrong way, or a step left out, is the usual slip.
Worked explanation 1
The art room orders 21 boxes of crayons at $3.95 a box. Which amount is closest to the total cost?
AA.
$63
BB.
$73
CC.
$93
DD.
$83
Answer: D
Answer: D ($83)
$3.95 is nearly $4, and 21 boxes is nearly 20 boxes plus one more. 21 × $4 = $84, and taking off 5c for each box (about $1) gives about $83. (Exactly, 21 × $3.95 = $82.95.)
The trap: $93 tempts children who round both numbers up a lot, or who slip on 21 × 4.
Why the other options are wrong
A ($63): Is about 16 boxes' worth, far too low.
B ($73): Is about 18 or 19 boxes' worth, still too low.
C ($93): Is more than 21 × $4, so it must be too high.
Worked explanation 2
A person blinks about 15 times a minute while awake and is awake for about 16 hours a day. Which is the best estimate of how many times they blink in one week?
AA.
10 000
BB.
100 000
CC.
1 000 000
DD.
25 000
Answer: B
Answer: B (100 000)
In an hour: 15 × 60 = 900 blinks. In a day: 900 × 16 = 14 400. In a week: 14 400 × 7 is about 100 000 (exactly 100 800).
The trap: 10 000 tempts children who work out one day's blinks (about 14 000) and forget to multiply by 7.
Why the other options are wrong
A (10 000): Is less than one day's blinking.
C (1 000 000): Is about ten times too big, a slip with the zeros.
D (25 000): Is less than two days' blinking.
Worked explanation 3
A shearer takes about 2 minutes 50 seconds to shear one sheep. The shearer works for 7 hours 45 minutes in a day, not counting breaks. Which is the best estimate of how many sheep the shearer can shear in that day?
AA.
230
BB.
16
CC.
160
DD.
120
Answer: C
Answer: C (160)
7 hours 45 minutes is 7 × 60 + 45 = 465 minutes. Each sheep takes a little under 3 minutes, and 465 ÷ 3 = 155, so the shearer manages a few more than 155. The best estimate is 160. (Worked exactly, 465 minutes is 27 900 seconds, and 27 900 ÷ 170 is just over 164.)
The trap: 230 tempts children who use 2 minutes a sheep and drop the 50 seconds (465 ÷ 2 is about 232).
Why the other options are wrong
A (230): Drops the 50 seconds and divides by 2 minutes.
B (16): Is about ten times too small, a place-value slip.
D (120): Rounds the time per sheep up to 4 minutes.
Worked explanation 4
A garden sprinkler uses about 14 litres of water a minute. Ari runs it for 25 minutes every second day in January, starting on 1 January. Water costs about $3.20 for every 1000 litres. About how much does the sprinkler's water cost for January?
AA.
$18
BB.
$9
CC.
$36
DD.
$180
Answer: A
Answer: A ($18)
Every second day from 1 January to 31 January is 16 days. Each day uses 14 × 25 = 350 litres, so the month uses 16 × 350 = 5600 litres. That is 5.6 lots of 1000 litres, and 5.6 × $3.20 is about $18.
The trap: $36 tempts children who work out the cost as if the sprinkler ran every day of January.
Why the other options are wrong
B ($9): Is about half the real cost, as if it ran every fourth day.
C ($36): Treats the sprinkler as running every day of January.
D ($180): Is ten times too much, a slip when dividing by 1000.
When is estimating not enough?
When two options are close, a rough estimate can land between them. Then your child needs one more step: take back the rounding, or work one part exactly. In the crayon example, 21 lots of 4 gives a number just above the answer, and taking off a few cents a box settles it.
"Closest" and "best estimate" ask different things. Closest means the option nearest the exact answer, so precision can matter. Best estimate means a sensible round figure, so the exact answer may sit a little away from every option.
What traps should your child watch for?
Each slip below pushes the estimate the wrong way or the wrong size. If your child falls into one, name it together and use its check on the next few questions.
Rounding everything up. Each rounding pushes the answer the same way, and the error grows. Round some up and some down.
Stopping one step early. A question about a week or a month needs one more multiplication.
Dropping the seconds. Rounding a time down to the whole minute when it's nearly the next one makes the count far too big.
Counting every day. "Every second day" is about half the days in the month, and the starting day counts.
Working exactly when it isn't needed. A long multiplication uses time the rest of the test needs.
How fast should estimation be?
Quick, if your child rounds; slow, if they work it exactly. Edutest says many students will not finish every question, so seconds saved here buy time for harder questions.
If the rounded answer falls between two options and adjusting doesn't help, your child should choose the nearer one and move on. There are no marks lost for wrong or blank answers.
Shopping is the easiest practice. Before the total shows, your child rounds each item and says an estimate, then you compare. Travel times, recipe amounts and screen time over a week work the same way.
Ask for the size first ("hundreds or thousands?"), then the number. In the app, the estimation 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.
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 estimation is costing marks. It sits with the other kinds on the Numerical Reasoning sample questions page, and arithmetical reasoning covers word problems that need an exact answer.
