What is the additive identity for whole numbers?

(i) Natural numbers are all the numbers from $1$ onwards, i.e., $1, 2, 3, 4, 5, 6, \dots ..$ and are used for counting.

(ii) Whole numbers are all the numbers from $0$ onwards, i.e., $0, 1, 2, 3, 4, 5, 6, ...$

(iii) The smallest natural number is $1$ and the smallest whole number is $0$.

2. The successor:

The successor of a whole number is $1$ more than the whole number.

3. The predecessor:

The predecessor of a whole number is $1$ less than the whole number. There is no predecessor of zero in whole numbers.

4. Number Line:

(i) A number line is a horizontal line on which there are equally spaced points.

(ii) These points represent whole numbers starting from zero.

5. Properties of Whole Number:

If $a, b, c,$ etc are Whole numbers, then

(i) $a+b$ is a Whole number. [Closure property of addition]

(ii) $a\times b$ is a Whole number. [Closure property of multiplication]

(iii) $(a-b)$ may or may not be a Whole number.

(iv) $a÷b$ may or may not be a Whole number.

(v) $a+b=b+a$ [Commutativity of addition]

(vi) $a\times b=b\times a$ [Commutativity of multiplication]

(vii) $a-b$ is not equal to $b-a$ if $a \mathrm{and} b$ are unequal.

(viii) $a÷b$ is not equal to $b÷a$ if $a \mathrm{and} b$ are unequal.

(ix) $a÷b=b÷a$ if and only if $a=b$.

(x) $(a+b)+c=a+(b+c)$ [Associativity of addition]

(xi) $a\times (b\times c)=(a\times b)\times c$ [Associativity of multiplication]

(xii) $a\times (b+c)=a\times b+a\times c$ [Distributivity of multiplication over addition]

(xiii) $a\times (b-c)=a\times b-a\times c$, if $b>c$ [Distributivity of multiplication over subtraction]

(xiv) $a+0=a=0+a$ [Existence of additive identity]

(xv) $a\times 0=0=0\times a$ [Existence of multiplicative identity]

(xvi) $a\times 1=a=1\times a$

(xvii) $a÷1=a$

(xviii) In general $(a-b)-c\ne a-(b-c)$

(xix) In general $(a÷b)+c\ne a÷ (b÷c)$

(xx) If $a$ is dividend, $b(\ne 0)$ divisor, $q$ quotient and $r$ remainder, then $a=bq+ r$.