Answer :

(a) 5 = 4+ 1. (3 ,2 )

(b) 10 = 7+3 (7,3 )

(c) 15 = 9 + 6 ( 2, 13 )

(d) 20 = 17 + 3 (17,3 )

(e) 20 = 13+ 7 (13, 7)

- Q.1. What is the sum of any two (a) Odd numbers? (b) Even numbers?
- Q.2 State whether the following statements are True or False: (a) The sum of three odd numbers is even. (b) The sum of two odd numbers and one even number is even. (c) The product of three odd numbers is odd. (d) If an even number is divided by 2, the quotient is always odd. (e) All prime numbers are odd. (f) Prime numbers do not have any factors. (g) Sum of two prime numbers is always even. (h) 2 is the only even prime number. (i) All even numbers are composite numbers. (j) The product of two even numbers is always even.
- Q.3. The numbers 13 and 31 are prime numbers. Both these numbers have same digits 1 and 3. Find such pairs of prime numbers up to 100.
- Q.4. Write down separately the prime and composite numbers less than 20.
- Q.5. What is the greatest prime number between 1 and 10?
- Q.6 Express the following as the sum of two odd primes. (a) 44 (b) 36 (c) 24 (d) 18
- Q.7 Give three pairs of prime numbers whose difference is 2. [Remark: Two prime numbers whose difference is 2 are called twin primes].
- Q.8 Which of the following numbers are prime? (a) 23 (b) 51 (c) 37 (d) 26
- Q.9 Write seven consecutive composite numbers less than 100 so that there is no prime number between them.
- Q.10. Express each of the following numbers as the sum of three odd primes: (a) 21 (b) 31 (c) 53 (d) 61
- Q.12 Fill in the blanks: (a) A number which has only two factors is called a ______. (b) A number which has more than two factors is called a ______. (c) 1 is neither ______ nor ______. (d) The smallest prime number is ______. (e) The smallest composite number is _____. (f) The smallest even number is ______.

- NCERT solutions for class 6 maths chapter 1 Knowing Our Numbers
- NCERT solutions for class 6 maths chapter 2 Whole Numbers
- NCERT solutions for class 6 maths chapter 3 Playing with Numbers
- NCERT solutions for class 6 maths chapter 4 Basic Geometrical Ideas
- NCERT solutions for class 6 maths chapter 5 Understanding Elementary Shapes
- NCERT solutions for class 6 maths chapter 6 Integers
- NCERT solutions for class 6 maths chapter 7 Fractions
- NCERT solutions for class 6 maths chapter 8 Decimals
- NCERT solutions for class 6 maths chapter 9 Data Handling
- NCERT solutions for class 6 maths chapter 10 Mensuration
- NCERT solutions for class 6 maths chapter 11 Algebra
- NCERT solutions for class 6 maths chapter 12 Ratio and Proportion
- NCERT solutions for class 6 maths chapter 13 Symmetry
- NCERT solutions for class 6 maths chapter 14 Practical Geometry

- NCERT solutions for class 6 science chapter 1 Food: Where Does It Come From?
- NCERT solutions for class 6 science chapter 2 Components of Food
- NCERT solutions for class 6 science chapter 3 Fibre to Fabric
- NCERT solutions for class 6 science chapter 4 Sorting Materials into Groups
- NCERT solutions for class 6 science chapter 5 Separation of Substances
- NCERT solutions for class 6 science chapter 6 Changes Around us
- NCERT solutions for class 6 science chapter 7 Getting to Know Plants
- NCERT solutions for class 6 science chapter 8 Body Movements
- NCERT solutions for class 6 science chapter 9 The Living Organisms — Characteristics and Habitats
- NCERT solutions for class 6 science chapter 10 Motion and Measurement of Distances
- NCERT solutions for class 6 science chapter 11 Light, Shadows and Reflections
- NCERT solutions for class 6 science chapter 12 Electricity and Circuits
- NCERT solutions for class 6 science chapter 13 Fun with Magnets
- NCERT solutions for class 6 science chapter 14 Water
- NCERT solutions for class 6 science chapter 15 Air Around us