The idea in brief. Rounding looks at ONE digit, the one just to the right of the place asked: smaller than 5 keeps the place's digit, 5 or greater adds one to it, and every place to the right becomes a zero. Read backwards, that same digit fixes the range: the smallest number that rounds up has a 5 there, the greatest that rounds down has a 4 there and 9s after it.
Lesson video, with the working
Rounding whole numbers
3 min 09 s
The film teaches 2 questions in turn. Each question shows first; its working is written as the film explains it.
the digit is 5, so add 1 to the digit in the hundreds place
63 852 = 63 900 (to the nearest hundred)
Ans: 63 900
Example 1
The number of people at a match, rounded to the nearest thousand, is 38 000. (a) What is the smallest possible number of people at the match? (b) What is the greatest possible number of people at the match?
5 and greater than 5: round up, add 1 to the thousands digit
4 and smaller than 4: round down, the thousands digit stays
Ans: ['37 500', '38 499']
How to solve it
Find the place named in the question. For the nearest hundred, look at the tens digit.
If that next digit is 5 or greater, add 1 to the hundreds digit. Otherwise, keep the hundreds digit.
Put zeros in the places to its right. 63 852 rounds to 63 900 to the nearest hundred.
For the smallest number rounding to 38 000, use the first number that rounds up: 37 500.
For the greatest number, keep 8 thousands, use 4 hundreds, then the greatest tens and ones digits: 38 499.
Check the deciding digit at each end of the range.
The next digit decides. 5 and greater than 5 rounds up, and 4 and smaller than 4 rounds down.
Practice questions with worked solutions
Question 1 is free to try. The other 7 open in the free trial, each with its full working.
4 is smaller than 5, so keep the digit in the thousands place
27 486 = 27 000 (to the nearest thousand)
Answer: 27 000
For parents
How can I help my child understand P4 rounding numbers questions?
Your child rounds whole numbers to the nearest 10, 100 or 1000 and uses the approximately equal sign, ≈.
What your child learns here
Your child rounds whole numbers to the nearest 10, 100 or 1000 and uses the approximately equal sign, ≈. These are MOE Primary 4 whole numbers outcomes 1.5 and 1.6. Rounding replaces an exact number with a nearby multiple, making it useful for estimating and checking the size of an answer.
Identify the place requested before examining the digit immediately to its right, because rounding to tens and rounding to thousands answer different questions.
Round up when the deciding digit is 5 or greater, and round down when it is 4 or smaller, replacing the later digits with zeros.
Handle a change that passes through a nine, recognising that rounding can increase a place further to the left as well.
Use ≈ for an approximate value and reserve the equals sign for a statement that gives the same exact amount on both sides.
Find the smallest and greatest whole numbers that round to a stated value, testing the two boundary numbers against the rounding rule.
Does the answer make sense?
A whole number rounded to the nearest hundred must be a multiple of 100 and no more than 50 away from the original. When the original is exactly halfway between two hundreds, the rounded answer is the higher hundred.
How to practise these questions
The Basic questions round to a requested place, including a result that carries through a nine. Intermediate questions estimate sums and differences, form a number before rounding it and list even numbers consistent with a rounded value. The Challenge questions combine rounding with digit choices or a digit-sum condition. Have your child write down every condition before searching for possible original numbers. For an estimate, follow the requested order by rounding the given amounts before calculating with them. For a digit puzzle, test the completed candidate against both the rounding interval and the digit restrictions. The check should confirm the entire answer, not just its rounded value.
Questions parents ask
Which digit should my child look at when rounding? First locate the requested place, then inspect the next digit to its right. For the nearest hundred, the tens digit decides whether to round up or down. Your child should name both places so that the decision is connected to the question rather than a memorised position.
Is an estimate meant to be the exact answer? An estimate is an approximate amount that helps judge size or plan a calculation. If the question asks for an exact answer, your child still needs the exact calculation. Comparing the two can reveal a large discrepancy, but agreement with an estimate alone does not prove every digit.
How can my child check a range of possible original numbers? Round each proposed endpoint to the requested place. Both endpoints should give the stated rounded value. Then test the whole number just below the lower endpoint and just above the upper endpoint; these should round to the neighbouring values instead.
