# 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?

2,050

2,055

205.2

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.

## Problem 2

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

## Problem 3

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

## 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

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

What error did Han make?

Find the value of

.