If the compound interest on a certain sum of money for $3$ years at $5 \%$ p.a. is $Rs. 504.40$,find the corresponding simple interest. (In $Rs.$)

Which information given below is sufficient to know the principal amount if the difference between the $C.I.$ and $S.I.$ for $2$ years is $18$?
$(I)$ The rate is same at which an amount of $Rs. 1000$ becomes $1120$ in $2$ years under $S.I.$
$(II)$ The principal is $Rs. 2000$.

Find the compound interest on $Rs. 12500$ at $8 \%$ per annum for $9$ months compounded quarterly (in $Rs.$).

The difference between the simple interest and the compound interest (in ₹) on ₹ $600$ for $1$ year at $10 \%$ per annum,reckoned half-yearly is

The compound interest (in ₹) on ₹ $5,000$ for $3$ years at $10 \%$ per annum will amount to:

Rohit invested some amount at the rate of $6\%$ per annum and at the end of $3$ years he received ₹ $8730$ as simple interest. How much compound interest (in ₹) will he receive on the same amount and same rate of interest after $2$ years?