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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.
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).
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.
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.
The sign ^ denotes exponentiation, the sign - the base of the logarithm.