Understanding the Difference between CI and SI
Investing money in either Compound Interest (CI) or Simple Interest (SI) can yield different returns over time due to the way interest is calculated. Let's break down the given scenario to understand the difference between CI and SI on a certain sum of money invested for 3 years at 6% per annum.

Given Information
- Time period (n) = 3 years
- Rate of interest (r) = 6% per annum
- Difference between CI and SI = $110.16

Calculating the Principal
To find the principal amount, we can use the formula for the difference between CI and SI:
Difference = P[(1 + r/100)^n - 1] - P(r/100)n
Substitute the given values:
$110.16 = P[(1 + 6/100)^3 - 1] - P(6/100)3
$110.16 = P[(1.06)^3 - 1] - P(0.06)3
$110.16 = P(1.191016) - P(0.18)
$110.16 = 0.191016P
P = $577.39
Therefore, the principal amount invested is $577.39.

Conclusion
In this scenario, the principal amount invested is $577.39. Understanding the difference between CI and SI is essential for investors to make informed decisions about their investments. Compound interest typically yields higher returns over time compared to simple interest due to the compounding effect. It is crucial to consider the time period, interest rate, and principal amount when calculating the returns on an investment.