For a 10% rate compounded annually for 2 years, the effective interest rate is:
\[ 10 + 10 + \frac{10 \times 10}{100} = 21\% \]
Thus, the total accumulated amount is 121% of the principal.
If 121% of $P = 24200$, then 1% of $P = 200$, and the 100% principal $P = 20000$.