Pre-Algebra builds compound interest from percents: the interest earned each period is added to the balance, so the next period earns interest on the interest too. Work a short problem year by year first, then use the formula with a calculator, rounding to the nearest cent. Half the sheet runs backward and asks how much to deposit now, and a few of those use continuous compounding.
$500 is invested at 10% compounded annually. Find the balance after 2 years.
Year 1: 10% of 500 is 50, so the balance is 550.
Year 2: 10% of 550 is 55, so the balance is 605.
The answer is $605.00.
Where students go wrong
Working it as simple interest by accident. Taking 10% of the original $500 each year gives $600, but the second year's interest is on $550, so the balance is $605.
Also called continuous compounding, interest formula or exponential growth.
What you can put on this worksheet
Compounded a set number of times a year
$1100 is invested at 5% compounded annually. Nothing is added or taken out for 8 years. Find the interest earned.→ $525.20
Compounded continuously
$1100 is invested at 5% compounded continuously. Nothing is added or taken out for 8 years. Find the interest earned.→ $541.01
How long it takes to double
How many years does it take money invested at 5% compounded semiannually to double?→ 14.0 years
The deposit needed now
How much must be invested now at 5% compounded annually to have $8000 in 16 years?→ $3664.89
Continuous compounding: the rate or the time
How long does it take $5500 to grow to $16500 at 7% compounded continuously?→ 15.7 years
Solve for the number of steps or the rate
A town of 59,000 people grows by 3.6% a year. After how many years does it have 70,413 people?→ 5 years
Questions about these worksheets
Yes. Every compound interest sheet is free to print and free to download as a PDF. There is no account to make, no email to hand over and no limit on how many you take.
Yes. The answer key prints on a second page, and you can choose whether it shows each question beside its answer or just the answers in a list.
Yes. Print straight from the page, or download the PDF and print that. The sheet is laid out for paper rather than squeezed off a screen, so there is room to work under each question, and the answer key comes out on its own page.
Pre-Algebra is usually taken around 7th or 8th grade, though schools vary and plenty of students meet it earlier or later. Pick the difficulty rather than the grade: the easy level suits a first lesson on it, the hard level suits review before a test.
Yes, as many as you like. The questions are built fresh each time rather than picked from a fixed set of files, so pressing Generate gives a new sheet. That is what you want for a second class, a retake, or two students sitting next to each other.
That is the closest comparison, and Kuta Software is good software. It is also paid software you install on a computer. These worksheets run in a browser tab for free, with no account and nothing to install. Like Kuta, the compound interest questions are generated when you ask for them rather than pulled from a fixed set of files, so two classes never get the same sheet, and the answer key comes with it.
Yes. There are three levels, and you can tick more than one for a sheet that mixes them, in which case the questions come out easiest first. The harder levels are not just larger numbers: they ask for something the easy ones do not.
You pick from 6: compounded a set number of times a year, compounded continuously, how long it takes to double, the deposit needed now, continuous compounding: the rate or the time and solve for the number of steps or the rate. Tick as many as you want and set how many of each, or let it spread them evenly.
Putting the yearly rate in without dividing it. Compounded monthly means one twelfth of the rate twelve times a year, not the whole rate twelve times, and the difference is enormous over twenty years.