Lesson 21 Zeros in the Standard Algorithm

    • Let’s subtract from numbers with several zeros.

Warm-up Which One Doesn’t Belong: Numbers with 0, 2, and 5

Which one doesn’t belong?

  1. 2,050

  2. 2,055

  3. 205.2

  4. 20,005

Activity 1 What If There is Nothing to Decompose?

Problem 1

Here are some numbers you saw earlier. Each number has at least one 0. From each number, 1,436 is being subtracted.
Make sense of the problems and explain to a partner.

  1. Subtract. Two thousand fifty, minus, one thousand four hundred thirty six, equals, six hundred fourteen.  
  2. Subtract. Two thousand fifty five, minus. one thousand four hundred thirty six, equals, six hundred nineteen.  

Problem 2

Use the approach in the first problem to find these two differences:

  1. subtract. two thousand, five, minus, one thousand, four hundred thirty six.
  2. subtract. twenty thousand, five, minus, one thousand, four hundred thirty six.

Problem 3

Find the value of each difference. Be prepared to explain your reasoning. If you get stuck, try subtracting using the expanded form.

  1. Subtract. eight thousand, thirty, minus, two thousand, six hundred, fifteen, equals. 
  2. subtract. eight thousand, thirty three, minus, two thousand, six hundred fifteen.
  3. subtract. eight thousand, three, minus, two thousand, six hundred fifteen.
  4. subtract. eighty thousand, three, minus, two thousand, six hundred fifteen.

Activity 2 What is Your Age?

Jada recorded the birth year of some of her maternal grandparents for a family history project.

family member

birth year

grandmother

1952

grandfather

1948

great-grandmother   

1930

great-grandfather

1926

As of this year, what is the age of each family member? Show your reasoning. Use the standard algorithm at least once.

Practice Problem

Problem 1

Here is how Han found

Subtract. Three hundred thousand, five hundred, twenty six, minus, four thousand, four hundred, seventy two, equals two hundred six thousand, fifty four.

  1. How can you tell by estimating that Han has made an error?

  2. What error did Han make?

  3. Find the value of .