Rounding Numbers

Rounding numbers is required when we deal with large numbers, for example, suppose the population of a district is 5834237, it is difficult to remember the seven digits and their order. But to get an idea of the size of the population of the district, we may remember the two digits on the left and put zeros for other digits. Thus, the population of the district can be conveniently remembered as 5800000.

We say that 5834237 has been round off to 5800000. Thus, 5800000 is a round number for the number 5834237, rounded off to the nearest lakh. If we remember the population as 5830000, we have rounded off the population on the nearest ten thousand.

Real life examples on rounding numbers:

(i) Ken’s new neighbor asked him his age. Ken said that he was fourteen years old.

His actual age was fourteen years two months and seven days.

(ii) Shelly told Keri that she weighs about 50 kg. Shelly’s exact weight was 52 kg.

(iii) Victor paid $45 for a pair of sports shoes. He told Ron, this pair of shoes cost me nearly$50.

In all this these statements, the numbers have been rounded. A rounded number is easy to remember and is a convenient figure for calculation.

While rounding numbers, the number 10 is very useful. We use it to think about place value. The number 5 is also important.

5 is half of 10.5 is halfway between 0 and 10.

These number lines show the halfway point between two numbers.

Label the number liner to show the halfway point between each pair of numbers.

Look at the folded number line.

Each peak shows a number ending in 5. These numbers are halfway between the two tens.

The tens are the base of each fold in the valleys.

The halfway number between 10 and 20 is 15.

The halfway number between 20 and 30 is 25.

If we place a counter on number 17, it would slide to 20 because 20 is the ten that is nearest to 17.

A counter placed on 27 will slide to 30.

A counter placed on 36 will slide to 40.

A counter placed on 14 will slide to 10.

A counter placed on 33 will slide to 30.

Halfway number such as 5 and 15 are rounded to the higher ten.

25 would be rounded to 30.

35 would be rounded to 40.

Numbers can be rounded to the nearest hundred, thousand, ten thousand and so on.

The halfway numbers on all the number lines contain a 5. The place of the digit 5 varies.

The rules for rounding numbers are the same for rounding to the nearest ten, hundred, thousand ……

If the given number is less than the halfway number, then round down. The rounded number will be less than the given number.

How do you round numbers?

Here we will discuss how to round numbers.

 (i) 435 is less than the halfway number, so it is rounded down. The rounded number is 400 which is less than the original number 435. When rounding, we replaced the digits in the ones and tens places by zeros. The digits in the hundreds place remains unchanged. If the given number is halfway or greater than the halfway number, then it is rounded up. The rounded number will be greater than the given number.
 (ii) Round 675 to the nearest hundred. 675 is greater than the halfway number, so it is rounded up to 700. The rounded number is greater than the original number 675. When rounding, we replaced the digits in the ones and tens places by zeros and increased the digit in the hundreds place by 1. A 3 digit number can be rounded to the nearest TEN or to the nearest HUNDRED.

(iii) Round 446 to the nearest ten.

Color the digit in the tens place 446

Look at the digit to the right of the colored digit. If it is greater than or equal to 5 then round up. If it less than 5 then round down.

6 > 5

446 will be rounded up to 450.

(iv) Round 726 to the nearest hundred.

Colored the digit in the hundreds place 726

Look at the digit to the right. It is greater than or equal to 5 then round up. If it is less than 5 then round down.
2 < 5

726 will be rounded down to 700.

The above method is convenient and helps us to remember very large numbers easily. It also simplifies calculation of large numbers.

There are certain situations where we have to give an idea about a number without actual calculation. This is called estimation.

Let us consider the following situations.

(a) There would be about 250 students going to picnic.

(b) India vs Pakistan cricket match was watched by about 50000 spectators in the stadium and about 40 million spectators on the T.V screen.

The figures stated above are estimated figures and are usually rounded off. We may round off a figure to the nearest ten, hundred, thousand and so on.

We will learn more about how a large number may be rounded off to the nearest 10, 100, 1000, 10000, 10000 etc...

Round off to Nearest 10.

Round off to Nearest 100.

Round off to Nearest 1000.

Rounding off Decimal Fractions.

Correct to One Decimal Place.

Correct to Two Decimal Place.

Worksheet on Rounding off number.

You might like these

• Round off to Nearest 100 | Rounding Numbers To Nearest Hundred | Rules

While rounding off to the nearest hundred, if the digit in the tens place is between 0 – 4 i.e. < 5, then the tens place is replaced by ‘0’. If the digit in the units place is equal to or >5, then the tens place is replaced by ‘0’ and the hundreds place is increased by 1.

• Round off to Nearest 1000 |Rounding Numbers to Nearest Thousand| Rules

While rounding off to the nearest thousand, if the digit in the hundreds place is between 0 – 4 i.e., < 5, then the hundreds place is replaced by ‘0’. If the digit in the hundreds place is = to or > 5, then the hundreds place is replaced by ‘0’ and the thousands place is

• Common Factors | Find the Common Factor | Worksheet | Answer

Common factors of two or more numbers are a number which divides each of the given numbers exactly. For examples 1. Find the common factor of 6 and 8. Factor of 6 = 1, 2, 3 and 6. Factor

• Divisibility Rules | Divisibility Test|Divisibility Rules From 2 to 18

To find out factors of larger numbers quickly, we perform divisibility test. There are certain rules to check divisibility of numbers. Divisibility tests of a given number by any of the number 2, 3, 4, 5, 6, 7, 8, 9, 10 can be perform simply by examining the digits of the

• Properties of Division | Division of Property Overview|Math Properties

The properties of division are discussed here: 1. If we divide a number by 1 the quotient is the number itself. In other words, when any number is divided by 1, we always get the number itself as the quotient. For example: (i) 7542 ÷ 1 = 7542 (ii) 372 ÷ 1 = 372

• Common Multiples | How to Find Common Multiples of Two Numbers?

Common multiples of two or more given numbers are the numbers which can exactly be divided by each of the given numbers. Consider the following. (i) Multiples of 3 are: 3, 6, 9, 12, 15, 18, 21, 24, …………etc. Multiples of 4 are: 4, 8, 12, 16, 20, 24, 28, …………… etc.

• Rules to Add Integers | Rules For Addition of Integers | Examples |

The rules to add integers are as follows: Rule 1: When the two integers have the positive sign, add the integers and assign the (+) sign to the sum.

• Round off to Nearest 10 |How To Round off to Nearest 10?|Rounding Rule

Round off to nearest 10 is discussed here. Rounding can be done for every place-value of number. To round off a number to the nearest tens, we round off to the nearest multiple of ten. A large number may be rounded off to the nearest 10. Rules for Rounding off to Nearest 10

• What are integers? | Negative and Positive Integers | Natural Numbers

What are integers? The negative numbers, zero and the natural numbers together are called integers. A collection of numbers which is written as …….. -4, -3, -2, -1, 0, 1, 2, 3, 4……… . These numbers are called integers.

• Word Problems on Multiplication and Division of Whole Numbers |Example

We will learn how to solve step-by-step the word problems on multiplication and division of whole numbers. We know, we need to do multiplication and division in our daily life. Let us solve some word problem examples.

• Worksheet on H.C.F. and L.C.M. | H.C.F. by Long Division Method | Ans

We will solve different types of problems given in the Worksheet on H.C.F. and L.C.M. I. Find highest common factor of the following by complete factorisation: (i) 48, 56, 72 (ii) 198, 360 (iii) 102, 68, 136 (iv) 1024, 576 (v) 405, 783, 513

• Multiplication by Ten, Hundred and Thousand |Multiply by 10, 100 &1000

To multiply a number by 10, 100, or 1000 we need to count the number of zeroes in the multiplier and write the same number of zeroes to the right of the multiplicand. Rules for the multiplication by 10, 100 and 1000: If we multiply a whole number by a 10, then we write one

• Addition of Integers | Adding Integers on a Number Line | Examples

We will learn addition of integers using number line. We know that counting forward means addition. When we add positive integers, we move to the right on the number line. For example to add +2 and +4 we move 4 steps to the right of +2. Thus, +2 +4 = +6.

Didn't find what you were looking for? Or want to know more information about Math Only Math. Use this Google Search to find what you need.

Recent Articles

1. Worksheet on Word Problems on Fractions | Fraction Word Problems | Ans

Jul 16, 24 02:20 AM

In worksheet on word problems on fractions we will solve different types of word problems on multiplication of fractions, word problems on division of fractions etc... 1. How many one-fifths

2. Word Problems on Fraction | Math Fraction Word Problems |Fraction Math

Jul 16, 24 01:36 AM

In word problems on fraction we will solve different types of problems on multiplication of fractional numbers and division of fractional numbers.

3. Worksheet on Add and Subtract Fractions | Word Problems | Fractions

Jul 16, 24 12:17 AM

Recall the topic carefully and practice the questions given in the math worksheet on add and subtract fractions. The question mainly covers addition with the help of a fraction number line, subtractio…

4. Comparison of Like Fractions | Comparing Fractions | Like Fractions

Jul 15, 24 03:22 PM

Any two like fractions can be compared by comparing their numerators. The fraction with larger numerator is greater than the fraction with smaller numerator, for example $$\frac{7}{13}$$ > \(\frac{2…