To express 10 to the power of 9, we write it as 109. This notation, known as exponential notation, signifies that we are multiplying the number 10 by itself 9 times. In mathematical terms, it can be written as:
109 = 10 × 10 × 10 × 10 × 10 × 10 × 10 × 10 × 10
The result of this multiplication is 1,000,000,000, which can also be referred to as one billion. Exponential notation is useful because it allows us to express very large or very small numbers in a compact form. For example, writing out 10 repeated nine times would be cumbersome compared to the neat expression of 10 to the power of 9.