1299.

\(\therefore\)   5 + 7 = 12.

To find 3 x 3
We have to multiply 3 by 3 i.e. 3 units x 3 (or 3 units 3 times). Let us start from 0, move 3 units to the right of 0.

After making 3 such moves, we reach at 9.
\(\therefore\)  3 x 3 = 9.

To find 2 x 6
We have to multiply 2 by 6 i.e. 2 units x 6 (or 2 units 6 times). Let us start from 0, move 2 units to the right of 0.

After making 6 such moves, we reach at 12.
\(\therefore\)  2 x 6 = 12.

To find 1+ 6
Let us start from 1. Since, we have to add 6 to this number, we make 6 jumps to the right of 1. Each jump being equal to 1 unit. After six jumps, we reach at 7.

\(\therefore\)  1 + 6 = 7.

To find 3 + 5
Let us start from 3. Since, we have to add 5 to this number, we make 5 jumps to the right of 3. Each jump being equal to 1 unit. After five jumps, we reach at 8.

\(\therefore\)  3 + 5 = 8.

Yes, all the natural numbers are also whole numbers.

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 3 + 6, start from 3 and make 6 jumps to the right by unit distance each. Then, we reach at 9.
          
So,  3 + 6 = 9.

Since we get predecessor by subtracting 1 and successor by adding 1.
So, Predecessor of 139 = 139 - 1 = 138 and successor of 139 = 139 + 1 = 140.

(a) Successor of 32 = 32 + 1 = 33
(b) Predecessor of 49 = 49 - 1 = 48
(c) Predecessor of 56 is 55
So, predecessor of the predecessor of 56 = 55 - 1 = 54
(d) Successor of 67 is 68
So, successor of the sucessor of 67 = 68 + 1 = 69
Hence, the sum of four numbers = 33 + 48 + 54 + 69 = 204.

Yes, if the product of two whole numbers is zero, then one or both of them will be zero. Since, we know that the product of any whole number with zero is always zero i.e. a x 0 = 0, where a is any whole number and 0 x 0 = 0. Some examples are as follows:

The given pattern is
                     1 = 12
               1 + 3 = 22
          1+ 3 + 5 = 32
    1+ 3 + 5 + 7 = 42
(a) Sum of first 12 odd numbers
1+ 3 + 5 + 7 + 9 + 11 + 13 + 15 + 19 + 21 + 23 + 25 = 122 = 1
(b) Similarly, sum of first 50 odd numbers = 502 = 2500.

The smallest number of 7-digit = 1000000
and the largest number of 4-digit = 9999
\(\therefore\) The difference between them
= 1000000 - 9999 = 990001

Let an odd natural number other than 1 be 3.
Predecessor of 3 = 3 - 1 = 2
Successor of 3 = 3 + 1 = 4
\(\therefore\) Product = 2 x 4 = 8
Now, LCM of predecessor and successor = 2 x 2 = 4
\(\therefore\) The greatest number which always divides the product of predecessor and successor of an odd natural number other than 1 is 4.

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

Zero (0) has no predecessor.

Let the whole number be x.
Now, according to the question,
x + 25 + 25 - x = 50.

We have, 786 x 3 + 786 x 7 = 786 x (3 + 7) = 786 x 10
                                         = 7860.

that, the largest 3-digit is 999.
\(\therefore\) Successor of 999 = 999 + 1 = 1000
So, 1000 is the successor of largest 3-digit number.