Thursday, April 6, 2017

CBSE Class 6 Maths - Ch2 Whole Numbers - NCERT Ex 2.3 (#cbsenotes)(#ncertanswers)

Whole Numbers

Chapter 2: Whole Numbers  

CBSE Class 6 Maths - Ch2 Whole Numbers - NCERT Ex 2.1 (#cbsenotes)(#ncertanswers)

NCERT Exercise 2.3 

CBSE Class 6 Maths - Chapter 2

Q1: Which of the following will not represent zero:

(a) 1 + 0
(b) 0 ✕ 0
(c)

  0
2

(d)
  10 - 10
2
Answer:
(a) [∵ 1 + 0 = 1]


Q2: If the product of two whole numbers is zero, can we say that one or both of them will be zero? Justify through examples.



Answer: Yes, if we multiply any number with zero the product will be zero.
Example:
2 ✕ 0 = 0,
15 ✕ 0 = 0,
22 ✕ 0 = 0

If both numbers are zero, then the result also be zero.
0 ✕ 0 = 0


Q3: If the product of two whole numbers is 1, can we say that one or both of them will be 1? Justify through examples.

Answer: If only one number be 1 then the product cannot be 1.
Examples:
5 ✕ 1  = 5,
14 ✕ 1 = 14,
7 ✕ 1  = 7
If both number are 1, then the product is 1
1 ✕ 1 = 1


Q4: Find using distributive property :
(a) 728 × 101
(b) 5437 × 1001
(c) 824 × 25
(d) 4275 × 125
(e) 504 × 35

Answer:

(a) 728 × 101
= 728 × (100 + 1)
= 728 × 100 + 728 x 1
= 72800 + 728
= 73528

(b) 5437 × 1001
= 5437 × (1000 + 1)
= 5437 × 1000 + 5437 × 1
= 5437000 + 5437
= 5442437

(c) 824 × 25
= 824 × (20 + 5)
= 824 × 20 + 824 × 5
= 16480 + 4120
= 20600

(d) 4275 × 125
= 4275 x (100 + 20 + 5)
= 4275 x 100 + 4275 x 20 + 4275 x 5
= 427500 + 85500 + 21375
= 534375

(e) 504 × 35
= (500 + 4) × 35
= 500 x 35 + 4 × 35
= 17500 + 140
= 17640

Q5: Study the pattern :
1 × 8 + 1 = 9 1234 × 8 + 4 = 9876
12 × 8 + 2 = 98 12345 × 8 + 5 = 98765
123 × 8 + 3 = 987

Write the next two steps. Can you say how the pattern works?
(Hint: 12345 = 11111 + 1111 + 111 + 11 + 1).

Answer: The next two steps are:
123456 × 8 + 6  = 987654
1234567 × 8 + 7 = 9876543

Pattern works like this:
1 × 8 + 1 = 9
12 × 8 + 2 = 98
123 × 8 + 3 = 987
1234 × 8 + 4 = 9876
12345 × 8 + 5 = 98765
123456 × 8 + 6 = 987654
1234567 × 8 + 7 = 9875643

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