The smallest whole number is zero (0).

To find 4 + 5
Let us start from 4. Since, we have to add 5 to this number, we make 5 jumps to the right of 4. Each jump being equal to 1 unit. After five jumps, we reach at 9.

\(\therefore\)  4 + 5 = 9.

Yes, the smallest natural number 1 has no predecessor because predecessor of 1 is (1 - 1 = 0) zero and zero is not a natural number.

For 6 - 3, start from 6 and make 3 jumps on the left by unit distance each. Then, we reach at 3.

So,     6 - 3 = 3.

Since, we get predecessor by subtracting 1 and successor by adding 1.
So, Predecessor of 243 = 243 -1 = 242 and successor of 243 = 243 + 1 = 244.

1, 0

25000

We have, 2n - 6 = 0
 2n = 6 \(\Rightarrow n=\frac{6}{2}=3\)

We start from 0, move 5 units at a time to the right, make 4 such moves. We reach at 20

So, 5 x 4 = 20.

We know that, predecessor is one less than the given whole number.
(a) Predecessor of 96 = 96 - 1 = 95
(b) Predecessor of 9998 = 9998 - 1 = 9997.

15 x 68 = 15 x (60 + 8)
= 15 x 60 + 15 x 8
(distributivity of multiplication over addition)
= 900 + 120 = 1020
17 x 23 = 17 x (20 + 3)
= 17 x 20 + 17 x 3
(distributivity of multiplication over addition)
=340+51=391
69 x 78 + 22 x 69
= 69 x 78 + 69 x 22
(commutativity of multiplication)
= 69 x (78 + 22)
(distributivity of multiplication over addition)
= 69 x 100 = 6900.

(i) 17136
(ii) 75708.

Rs 4055.

(a) Given, number of children, who got polio drops in March 2013 = 212583
Number of children, who got polio drops in next month = 216813
\(\therefore\) Difference of the number of children getting polio drops in two months
= 216813 - 212583 = 4230 children.
(b) Importance of pulse polio drops
The children are vaccinated for their protectior against deadly polio virus. All the babies below 5 yrs of age are given oral polio vaccine simultaneously, it helps to eradicate the virus.

We know that, the product of two whole numbers is always a whole number.
e.g. 0 x 0 = 0 and 1 x 2 = 2.

We have, 1 lakh = 100000
\(\therefore\) Predecessor of 100000 = 100000 - 1 = 99999.

If a and b are any two whole numbers, then a + b = b + a. This is commutative property.