0 (called "zero" or "nil") means "nothing exists" so 0 cannot ever be a real number, no matter whether we are considering positive or negative numbers.
So the smallest whole number is 1, also known as "one" or "unity".
Because it is the "magnitude" or "size" of the number which is being asked about in this kind of question - and not its "polarity" or "sign" - the previous sentence remains true no matter whether we are considering positive or negative whole numbers.
Another opinion
The term 'whole number' does not have a consistent definition. Various authors use it in one of the following senses:
Yet another opinion
Here are some relevant mathematical statements:
Those last four statements form a mathematical hypothesis - also known as a scientific theory or conjecture - about the smallest number that remains open to be disproved but so far has never been disproven.
Does anyone know anything more?
No. Whole numbers are counting numbers and zero.
negative or - number
Negative integers are whole numbers but not natural numbers. Mathematicians are undecided about zero. It is a whole number: some believe zero is a natural number, others do not.
it is simple an integer includes negative numbers including zero{-3,-2,-1,0,1,2,3}.but whole number has all non-negative numbers also including zero. {0,1,2,3}
An integer is a whole number (not a fraction) that can be positive, negative, or zero. A member of the set of positive whole numbers {1, 2, 3, . . . }, negative whole numbers {−1, −2, −3, . . . }, and zero {0}.
An integer. Integers are all of the whole numbers, all of the negative whole numbers, and zero.
No. Whole numbers are counting numbers and zero.
Integers can be positive, zero or negative. Whole numbers can only be zero or positive. All negative integers are not whole numbers, though they are the additive inverse of a whole number.
negative or - number
Negative integers are whole numbers but not natural numbers. Mathematicians are undecided about zero. It is a whole number: some believe zero is a natural number, others do not.
'0' is the only whole number that is not a counting number. Negative integers do not belong to whole numbers.
Positive and negative whole numbers and zero are integers. Zero is neither negative or positive.
it is simple an integer includes negative numbers including zero{-3,-2,-1,0,1,2,3}.but whole number has all non-negative numbers also including zero. {0,1,2,3}
An integer is a whole number (not a fraction) that can be positive, negative, or zero. A member of the set of positive whole numbers {1, 2, 3, . . . }, negative whole numbers {−1, −2, −3, . . . }, and zero {0}.
Integer: Negative numbers, zero, positive numbers. NO fractions/decimals Natural: Positive numbers. NO zero, negative numbers, fractions/decimals. Whole number: Positive numbers, zero. NO negative numbers, fractions/decimals. Therefore, a natural, rational, whole integer, would be: 1, 2, 3, 4, 5, 6, 7, ...
even, whole, non-negative numbers. (zero is not a natural number)
A counting number is one you would use normally, as in 1,2,3,4,5... not including zero. A whole number includes zero, but is not a negative integer.