6th Class Mathematics Decimals Operations on Decimals

   Operations on Decimals  

 

 

    Addition of Decimals

Consider the following decimal numbers 45.56, 23.5. The addition of the decimals is

  

(Unlike decimal is first converted into like decimal)  

 

 

Add the following decimals: 34.45, 45.67, 32.1.

(a) 113.23                                           

(b) 114.24

(c) 112.22                                            

(d) None of these

(e) All of these  

 

Answer: (c)                

Explanation                

	34.45
	45.67
+	32.10
	112.22

 

 

Subtraction of Decimals

Consider the following decimal numbers 56.23 and 45.1. The subtraction of thedecimal numbers is 56.23 -  45.1 =

(Unlike decimal is first converted into like decimal)  

 

 

Mariam had Rs 123 and 75 paise, she spent Rs 23 and 50 paise on purchasing fruits. How much money she has now?

(a) Rs 100 and 25 paise  

(b) Rs 99 and 25 paise

(c) Rs 99 and 50 paise    

(d) None of these

(e) All of these  

 

Answer: (a)                

Explanation                       

Rs 123.75 - Rs 23.50 = Rs 100 and 25 paisa.   

 

 

Multiplication of Decimals 

Consider the following decimals 34.48 and 12.24. Multiply by omitting decimal Point, now, put the decimal before four digits (Each has Two decimal places) from the right of resulting product = 422.0352.  

 

 

The product of the following fractions, 234.567 and 123.7 is?

(a) 29016.9372                                  

(b) 29015.9373                

(c) 29015.9379                 

(d) None of these

(e) All of these  

 

Answer: (c)

Explanation

 

 

 

Division of Decimals

Quotient of division of a whole number by a decimal number is obtained by placing number of zeroes in dividend for each decimal place digit of divisor. Division of 4565 by 3 

one zero has been placed in dividend for one decimal place of divisor.

Quotient of division of a decimal number by a whole number is obtained by placing number of zero for each place digit of dividend in divisor.

Division of 3.5 by a whole number  one zero has been placed in divisor for one decimal place of dividend.  

 

Quotient of Division of a Decimal Number by a Decimal Number is Obtained by the following steps:

Step 1:   Decimal point of the divisor is moved to right until it becomes a whole number.

Step 2:   Decimal point of the dividend is moved to right as same as the number of places have been moved in divisor.

Step 3:   Multiply both divisor and dividend by a number to get whole numbers if necessary.

Step 4:   Put decimal point in the quotient by counting total number of decimal places for both dividend and divisor as shown below:

Division of 587.87 by

Division of decimal number 456.78 by a whole number 67 by long division method.   

              = 6.817  

 

 

Rs 456.75 is equally divided among 7 people. How much money each person will receive?

(a) Rs  65.25                                       

(b) Rs 65.23

(c) Rs 65.26                                        

(d) none of these                

(e) All of these                

 

Answer: (a)                

Explanation  

                

 

 

 

An electric switch board contains 67876 switches. A small switch board is made up of 4 switches. Find the number of such switch boards which can be made from the total number of switches.                

(a) 3456                                               

(b) 16969                

(c) 6785                                               

(d) 11534                

(e) None of these                

 

Answer: (b)                

Explanation

The total number of switch board made by 67876   

 

 

Three pieces of wire, 34 m 3 cm, 4 m 5 cm and 3 m 5 cm have been joined each other. The total length of the wire is? 

(a) 41.13                                              

(b) 41.23

(c) 41 m                                               

(d) all of these

(e) none of these             

 

Answer (A)

Explanation 

Metre	Cm
34	3
4	5
3	5
41	13

 

 

  Simplify:

(a) 4.452                                              

(b) 4.321

(c) 4.134                                              

(d) all of these

(e) None of these   

 

Answer (a)

Explanation

 

 

 

Simplify: 0.001 + 1 + 0.01 + 1.

(a) 2.142                                              

(b) 2.011                

(c) 2.9                                                   

(d) All of these                 

(e) None of these

 

Answer: (b)

Explanation 0.001 +1 +0.01 +1 =2.011.  

 

 

Evaluate,

(a) 21.898                                           

(b) 21.011

(c) 13.134                                            

(d) All of these

(e) None of these  

 

Answer: (a)                

Explanation

 

 

 

Representation of decimal number 5.2 is obtained on number line by which one of the following?

(a) By dividing distance between 5 to 6 into ten equal parts

(b) By multiplying distance between two points on number line

(c) By adding distance between two points on number line

(d) All of these

(e) None of these  

 

Answer: (a)

Explanation

The position of 5.2 on the number line is obtained by dividing the distance between 5 and 6 into 10 equal parts.  

 

 

Number line is divided into how many number of equal division if the decimal part of the decimal number is three digit number.

(a) 8                                                      

(b) 10

(c) 11                                                    

(d) All of these

(e) None of these  

 

Answer: (b)                

Explanation

If the decimal part of a decimal number is three digits number then the number line will be divided into 10 equal parts.  

 

 

Whole part of a decimal number is obtained from which one of the following parts of decimal number?

(a) Among the digits                      

(b) Left side from decimal

(c) Right side from decimal        

(d) All of these

(e) None of these  

 

Answer: (b)                

Explanation

The number at the left side of decimal point is the whole part of the decimal number.                                                                 

 

 

Decimal part of a decimal number is obtained from which one of the following parts of decimal number?                                

(a) Right side from decimal         

(b) Left side from decimal               

(c) Among the digits                      

(d) All of these

(e) None of these                                                       

 

Answer: (a)                

Explanation

The number at the right side of decimal point is the decimal part of the decimal number.  

 

 

The decimal number 3.5 is exactly between which one of the following numbers on the number line?

               

(a) 3 and 4                                          

(b) 4 and 5

(c)  1 and 2                                         

(d) All of these

(e) None of these  

 

Answer: (a)

Explanation        

3.5 is greater than 3 but less than 4. Therefore, it will come between 3 and 4  

 

 

Four tenths and three hundredths is denoted in numbers by which one of the following?                                               

(a) 43.00                                              

(b) 00.43

(c) 4.300                                              

(d) All of these

(e) None of these  

 

Answer: (b)                

Explanation  

The decimal number 00.43 has four tenths and three hundredths.  

 

 

In which one of the following numerations system the place value of digit ls increase^ ten times from left to right?                

(a) Roman numeration                 

(b) Alphabetical numeration                

(c) Decimal numeration                

(d) All of these

(e) None of these  

 

Answer: (c)  

Explanation

The place value of digit at tens place is always ten times greater than the place value of digit at unit place and the place value of digit at hundreds place is 10 times greater than the place value of digit at hundreds place.      

 

 

  Write the shortest form of the following:

 

(a) 4508.706                       

(b) 4507.705

(c) 4509.707                       

(d) All of these

(e) None of these  

 

Answer: (a)  

Explanation

 

 

 

Change the fraction  into decimal.

(a) 0.01                                                

(b) 0.001

(c) 0.714                                              

(d) All of these

(e) None of these  

 

Answer: (c)  

Explanation

The decimal form of  

 

 

23 kg, 450 grams of rice is denoted by which one of the following options?

(a) 23.045kg                                       

(b) 23.450kg

(c) 23.045kg                                       

(d) All of these

(e) None of these  

 

Answer: (b)                

Explanation

The decimal form of 23 kg and 450 grams = 23.450 kg.      

 

 

• The first decimal system was introduced by Sumerians.
• Decimal is the latin word.
• One decimal number may or may not have whole part.
• Decimal number system is used by most of the countries in the world.
• Decimal part of a decimal number may or may not have repeating decimal.    

 

 

• Right sided numbers from decimal point are always less than 1.
• Numbers written in decimals are called decimal numbers or decimal.
• Decimal points should be vertically allied while adding or subtracting two or more decimal numbers.
• The fractions, having denominators 10, 100 and 1000 etc. are converted into decimal numbers by placing decimal point among the numerator. Division of a decimal number by a whole number is performed by placing zero in divisor for each one decimal place of dividend.