Lesson 4 Another Look at the Standard Algorithm

    • Let’s subtract from numbers with zeros.

Warm-up Number Talk: Differences

Find the value of each difference mentally.

Activity 1 Lots of Zeros

Problem 1

Find the value of each difference.

  1. subtraction algorithm 700-16
  2. subtraction algorithm 7,000-16
  3. subtraction algorithm 700,000-16

Problem 2

Find the number that makes each expression true.

  1. addition algorithm 43+ blank space=200
  2. addition algorithm 43+ blank space=2,000
  3. addition algorithm 43+ blank space=20,000
  4. addition algorithm 43+ blank space=200,000

Activity 2 Ways of Finding Differences

To find the value of , Priya and Han set up their calculations differently.

subtraction algorithm 20,000-472
addition algorithm 472+ blank space=20,000
  1. Use both methods to find the difference of 20,000 and 472.

  2. Kiran uses another method. Explain how Kiran found the value of .

  3. Which method do you prefer? Or do you prefer another way? Explain your reasoning.

  4. Find the value of . Show your reasoning.