Math Adventures/Compound Interest

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In 1683 Jacob Bernoulli considered the following problem:

An account starts with $1.00 and pays 100 percent interest per year. If the interest is credited once, at the end of the year, the value of the account at year-end will be $2.00. What happens if the interest is computed and credited more frequently during the year?

Calculate the year-end value of the account if the interest in credited twice per year.

  • Once per month?
  • Once per week?
  • Once per day?
  • Every hour?
  • Continuously?

Do you recognize that number?

Answer:

If there are n compounding intervals, the interest for each interval will be 100%/n and the value at the end of the year will be $1.00 × (1 + 1/n)n

For continuous compounding the formula becomes:

Notes