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8th grade How saving a little each month grows: simple and compound interest worksheet

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How saving a little each month grows: simple and compound interest

Grade 8 Math Worksheet - Challenge Me

NameDate

Circle the best answer, or write your answer on the line.

  1. 1.05 × 1.05 × 1.05 × 1.05 × 1.05 ≈ 1.28. Bo compares two pretend accounts that each start with $1,000 and get no deposits. A earns 6% simple interest; B earns 5% compound interest. Which has more after 5 years, and by about how much?

    • Account A, by about $20
    • Account A, by about $300
    • Account B, by about $20

  2. 1.05¹⁰ ≈ 1.63. Esme compares two pretend accounts that each start with $1,000 and get no deposits. A earns 6% simple interest; B earns 5% compound interest. Which has more after 10 years, and by about how much?

    • Account B, by about $630
    • Account A, by about $30
    • Account B, by about $30

  3. 1.04²⁰ ≈ 2.19. Jun compares two pretend accounts that each start with $1,000 and get no deposits. A earns 5% simple interest; B earns 4% compound interest. Which has more after 20 years, and by about how much?

    • Account A, by about $190
    • Account B, by about $1,190
    • Account B, by about $190

  4. 1.08⁵ ≈ 1.47. Kira compares two pretend accounts that each start with $1,000 and get no deposits. A earns 10% simple interest; B earns 8% compound interest. Which has more after 5 years, and by about how much?

    • Account B, by about $30
    • Account A, by about $500
    • Account A, by about $30

  5. Read this first

    Growth table

    $40 deposited at the start of each month, 6% a year compounded monthly, balances rounded to the dollar (Years | Deposits so far | Balance): 10 | $4,800 | ≈ $6,588; 20 | $9,600 | ≈ $18,574; 30 | $14,400 | ≈ $40,382.

  6. Luz reads Mr. Dunn's pretend college fund, which gets $40 each month. How much more interest does it earn in years 20 to 30 than in years 10 to 20?

  7. Growth table

    $100 deposited at the start of each month, 5% a year compounded monthly, balances rounded to the dollar (Years | Deposits so far | Balance): 10 | $12,000 | ≈ $15,593; 20 | $24,000 | ≈ $41,275; 30 | $36,000 | ≈ $83,573.

  8. Milo reads Ms. Hale's pretend retirement plan, which gets $100 each month. How much more interest does it earn in years 20 to 30 than in years 10 to 20?

  9. Growth table

    YearAccount AAccount B
    1$130$125
    2$160$156.25
    3$190$195.31
    4$220$244.14
    5$250$305.18

  10. Ren compares two pretend accounts that each start with $100. A earns 30% simple interest; B earns 25% compound interest. In which year does B first hold more than A?

  11. Tala compares two pretend accounts that each start with $200. A earns 25% simple interest; B earns 20% compound interest. In which year does B first hold more than A?

  12. Zee compares two pretend accounts that each start with $100. A earns 20% simple interest; B earns 15% compound interest. In which year does B first hold more than A?

  13. Ari compares two pretend accounts that each start with $200. A earns 30% simple interest; B earns 20% compound interest. In which year does B first hold more than A?

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8th grade How saving a little each month grows: simple and compound interest worksheet – printable
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About this worksheet

How saving a little each month grows: simple and compound interest. Every version has 10 questions, and the answer key prints on the second page.

What your child will learn

  • I can use a balance table to find the starting amount and the yearly gain of a simple-interest account, and predict a later balance.
  • I can tell a simple-interest table (equal gains) from a compound-interest table (growing gains), and extend a table whose balance is multiplied by the same number each year.
  • I can compare simple and compound interest for the same amount and say which account has more, and by how much.
  • I can read a table of monthly saving plans and reason about the interest in it, without calculating the balances myself.

Standard: state-only

Words to know

deposit: Money put into the account.

balance: All the money in the account now.

simple interest: Interest on the starting amount only, the same dollars every year.

compound interest: Interest on everything in the account, so interest earns interest.

growth table: A table of the balance in each year.

Common mistakes

Treated the balance as if it grows in proportion to the years, so ten years means ten times as much as one year. With simple interest the account already holds its starting amount and adds the same dollars each year.

Found the yearly gain times the years but left out the amount the account started with.

Started from the year 3 balance but added the gain for all the years, not only the years after year 3.

What to say

Ask: what does it start with, and what does it add each year?

Ask: what was in the account in year 0, and does the balance still include it?

Ask: how many years have already been counted in the last row of the table?

Questions parents ask

What is the most common mistake with how saving a little each month grows: simple and compound interest?

Treated the balance as if it grows in proportion to the years, so ten years means ten times as much as one year. With simple interest the account already holds its starting amount and adds the same dollars each year.

How can I help my child with how saving a little each month grows: simple and compound interest?

Ask: what does it start with, and what does it add each year?

Are these 8th grade math worksheets free to print?

Yes. All 6 printable versions at each level are free to print, with the answer key, and no account is needed.

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