In this lesson, we observed that when we multiply a positive power of 10 by $\frac{1}{10}$, the exponent decreases by 1. For example, $10^8 \boldcdot \frac{1}{10} = 10^7$. This is true for any power of 10. 

By using the rule $10^n\boldcdot 10^m=10^{n+m}$ with this example, we see that: $10^8\boldcdot 10^{\text-1}=10^7$.

Notice that for the exponent rules we have developed to work, then $\frac{1}{10}$ must equal $10^{\text-1}$.