Rounding

Imagine you’re carrying out a rabbit census, and you count 2,988 rabbits. Reporting this exact number each time could be hard to remember. To make it easier to talk about, you could say there are approximately 3,000 rabbits.

Why 3,000 and not 2,000? Because 2,988 is closer to 3,000 than it is to 2,000.

How to Round to the Nearest 10, 100 or 1,000

The concept of rounding can be applied to different levels of precision, not just whole numbers. You can round numbers to the nearest 10, 100 or 1,000, or even decimal places.

• Rounding to the Nearest 10: If you’re rounding the number 1,432 to the nearest 10, you’ll see that it falls between 1,430 and 1,440. The number 1,432 is closer to 1,430, so that’s your rounded figure.

• Rounding to the Nearest 100: The number 1,432 falls between 1,400 and 1,500 when rounding to the nearest 100. It is closer to 1,400, so that would be your rounded figure.

• Rounding to the Nearest 1,000: The number 1,432 falls between 1,000 and 2,000 when rounding to the nearest 1,000. It’s closer to 1,000, so that would be your rounded number.

The Rule of 5

When rounding, the unit value (the last digit in the number) is important.

• If the unit value is between 1 and 4, you round down

• If the unit value is between 5 and 9, you round up

Money and Rounding

Rounding and estimation are useful skills to have when handling money. Suppose you’re out shopping and you pick up three items priced at £12.99, £9.99 and £4.99.

Rounding these to £13.00, £10.00, and £5.00 respectively makes calculating your total expenditure easier. In this case, you’d approximate your total spending as £28.00. This is a much quicker calculation, although slightly less accurate.

Practice Questions

Question 1:

Round 76 to the nearest 10.

Solution

76 falls between 70 and 80 but is closer to 80. Therefore, the rounded number is 80.

---

Question 2:

Round 254 to the nearest 100.

Solution

254 is between 200 and 300 but is closer to 300. Hence, the rounded number is 300.

---

Question 3:

Round 9,623 to the nearest 1,000.

Solution

9,623 falls between 9,000 and 10,000 and is closer to 10,000. So, the rounded number is 10,000.

---

Question 4:

You’re shopping for items priced at £6.49, £11.25 and £19.80. What is the estimated total cost after rounding each item to the nearest £1?

Solution

Rounding to the nearest £1, the items become £6, £11 and £20. Adding these up, the estimated total cost is £37.