**Smallest Whole Number**

A whole number is a number that is not a fraction or a decimal. It is a non-negative integer that does not have any decimal or fractional part. Whole numbers include zero and all positive numbers without any decimal places.

The smallest whole number is zero (0). It is the starting point of the whole number system and is the only whole number that is neither positive nor negative. Zero is often referred to as the "identity element" because when it is added to or subtracted from any number, the result remains unchanged.

**Properties of Zero**

Zero has some unique properties that make it special in mathematics:

1. **Additive Identity**: Zero is the additive identity for whole numbers. When you add zero to any whole number, the result is the same number. For example, 5 + 0 = 5 and 100 + 0 = 100.

2. **Multiplicative Property**: Zero has the property that when multiplied by any whole number, the result is always zero. For example, 5 x 0 = 0 and 100 x 0 = 0.

3. **Division Property**: Division by zero is undefined. It is not possible to divide any number by zero and get a meaningful result. For example, 5 ÷ 0 is undefined.

**Why is Zero the Smallest Whole Number?**

Zero is the smallest whole number because it is the starting point of the whole number system. It is smaller than any positive whole number because it represents the absence of quantity. All other positive whole numbers are greater than zero.

Additionally, zero does not have a negative counterpart in the whole number system. Negative whole numbers are introduced in the integer system, which includes numbers less than zero.

In conclusion, the smallest whole number is zero. It is the starting point of the whole number system, has unique properties, and is smaller than any positive whole number.