Exercise-2.3
Q1. Which of the following will not represent zero:
(a) 1 + 0 (b) 0 × 0 (c) 0/2 (d) 10 -10/2
Solution:
(a) 1 + 0 = 1
So, it is not represent zero
(b) 0 × 0 = 0
it is represent zero
(c) 0/2 = 0
it is represent zero
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.
Solution:
Yes, we know that the product of any whole numbers with zero is always zero.
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.
Solution:
If only one number be 1 then the product cannot be 1.
Examples:
Here we see that one of two is 1 then product will be always second number.
If both numbers are 1, then the product is 1
Q4. Find using distributive property :
(a) 728 × 101 (b) 5437 × 1001 (c) 824 × 25 (d) 4275 × 125 (e) 504 × 35
Solution:
(a) 728 × 101
= 728(100 + 1)
= 728 × 100 + 728 × 1
= 72800 + 728
= 73528
Solution:
(b) 5437 × 1001
= 5437(1000 + 1)
= 5437 × 1000 + 5437 × 1
= 5437000 + 5437
= 5442437
Solution:
(c) 824 × 25
= 824(20 + 5)
= 824 × 20 + 824 × 5
= 16480 + 4120
= 20600
Solution:
(d) 4275 × 125
= 4275(100 + 20 + 5)
= 4275 × 100 + 4275 × 20 + 4275 × 5
= 427500 + 85500 + 21375
= 534375
Solution:
(e) 504 × 35
= (500 + 4) × 35
= 500 × 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).
