Compound Interest Part -2 how to do previous year questions logically in Mind

1
The compound interest on a certain sum for 2 years is 410, and the simple interest for the same period is 400. find the principal and the rate of interest?
Ans P= 4000 and R=5 %
2
The compound interest on a sum for 2 years is Rs. 832 and the simple interest on the same sum for the same period is Rs. 800. The difference between the compound interest and the simple interest for 3 years will be what ?
Ans 98.56

[sanjusharma]

Gazab or Shaandaaaar vedio V can solve without pen and U made my imagination so powerful to solve si ci questions in mind by clearing my Thnx a lot sir.... Lot of respect for u Your vedios r prolific and

[satishkumarranjan]

sir please solve for 4 years type questions