You will need
• calculator
Instruction
1
Use for calculating compound interest by the following formula summa=s×(1+p/100)^n, where the summa – the ultimate profit, s is the original amount of the Deposit, p – annual interest, that is interest rate, n is the number of years, months, days (period). For example, suppose you opened an account and deposited the R. of 10,000 at 5% per annum for 3 years. To see how much money is in your account at the end of the term, use the above formula, that is summa=10000×(1+5/100)^3=11576,25 R. Then your profit after 3 years will be equal to 11576,25−10000=1576,25 R.
2
Use the following formula to calculate compound interest for different interest periods: summa=s×(1+(p/100)×(g/y))^n, where g is the number of days the period which is made through capitalization, that is, the accrual of interest, thus, g=30, if interest is credited monthly, and g=90, if the capitalization of interest is quarterly, y is the number of days in the year (365 or 366 days).
3
For better understanding, consider an example. Let you open a Deposit at 6% per annum, the capitalization of interest is carried out monthly, initially at the expense you put 10,000 p. Then your amount in the account after 4 months will be summa=10000×(1+(6/100)×(30/365))^4=10198,72 R. now Let your contribution 10000 p opened at 6% per annum with interest capitalization every quarter. Then the amount of the contribution after six months will be summa=10000×(1+(6/100)×(90/365))^2=10298,08 R. Here, g=2, as in six months with this type of capitalization the interest would be charged twice.
4
Using this formula, we can Express the interest rate and the number of months (years). To calculate interest, use the formula p=((summa/s)^(1/n)-1)×100. For example, by what percentage you need to put the amount of 10 000 p. so after 5 years on the score was 15000 p – p=((15000/10000)^1/5−1)×100≈8,5%. To calculate period, use the following formula n=log<1+(p/100)>(summa/s). For example, how many years required to contribute at 10,000 R. at 6% per annum increased to 15000 p – n=log<1+(6/100)>(15000/10000)≈7 years.