On what sum does the difference between the compound interest

On what sum does the difference between the compound interest and the simple interest for 3 years at 10% is ₹ 31 ?

Let the sum be P.
R = 10% , T = 3 years
Using the given formula ,

S.I. =	P × R × T
	100

S.I. =	P × 10 × 3	=	3	P
	100		10

C.I. =			1 +	R		^T	− 1		P
				100

C.I. =			1 +	10		³	− 1		P
				100

C.I. =			11		³	− 1		P
			10

C.I. =		1331	− 1		P =	331	P
		1000				1000

∴ C.I. - S.I. = ₹ 31

⇒	331	P −	3	P = 31
	1000		10

⇒	(331 − 300)	P = 31
	1000

⇒	31	P = 31
	1000

⇒ P = 1000
∴ Sum = ₹ 1000
We can find required answer with the help of given formula :
Here, C.I. – S.I. = ₹ 31 , R = 10% , T = 3 years , P = ?

C.I. − S.I. = P		R		²	×		3 +	R
		100						100

31 = P		10		²	×		3 +	10
		100						100

31 = P ×	1	×	31
	100		10

P = ₹ 1000