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Adding decimals

Topic Notes

In this lesson, we will learn:

  • How to add decimal numbers using base ten (block) models
  • That adding decimal numbers is the same as adding whole numbers, which involves lining up the right place values and regrouping

Notes:

  • To add decimals with base ten (block) models:
    • Remember the three types of blocks used to represent the ones, tenths, and hundredths place values
      • "One whole" or hundred block = ones place value
      • Column (stick or rod) = tenths place value
      • Single square = hundredths place value
Adding Decimals
    • An addition statement is made of: addend + addend = sum
    • Count all of the blocks that you are adding up, altogether
    • Regroup to get to your final answer. 10 of any type of block will regroup into the next bigger type of block.

Adding Decimals

  • To add decimals, line up the decimal point to make sure you are adding the right place values in the same columns. Regroup (carry over) numbers whenever necessary.
    • Sometimes, you will have to write one or more zeroes to a number after the decimal point (trailing zeroes) when the addends don't have the same number of place values.