Where Does the Decimal Point Go?

Operations with Multidigit Decimals

Formative Assessment

Summary of the Math: Operations with Multidigit Decimals

Read and Discuss

  • Adding or Subtracting Decimals
    • Line up the digits according to place value.
    • Line up the decimal points.
    • “Carry” regrouped numbers from one column to the next, just as you do when adding or subtracting whole numbers.
  • Multiplying Decimals
    • Multiply decimals using the same method that you use to multiply whole numbers. Ignore the decimal points (do not line up the decimal points).
    • After multiplying, use estimation to place the decimal point. Or, count the total number of decimal places in the numbers you multiplied. In your product, start from the right and move one place to the left for each of the decimal places you counted. Place the decimal point at the resulting location.
  • Dividing Decimals
    • Multiply the divisor and the dividend by the same power of 10. The power of 10 should be large enough so that the resulting numbers are whole numbers. Then divide using the long division method. Use estimation to make sure your answer makes sense.

Can you:

  • Explain how to add and subtract decimals?
  • Explain how to multiply and divide decimals?
  • Explain how estimating can help when you are performing operations with decimals?