Lesson 10

Using Long Division

Let’s use long division.

Problem 1

Kiran is using long division to find \(696 \div 12\).

Long division. 696 divided by 12.

He starts by dividing 69 by 12. In which decimal place should Kiran place the first digit of the quotient (5)?

A:

Hundreds

B:

Tens

C:

Ones

D:

Tenths

Problem 2

Here is a long-division calculation of \(917 \div 7\).

Example division problem 917 divided by 7.
  1. There is a 7 under the 9 of 917. What does this 7 represent?
  2. What does the subtraction of 7 from 9 mean?
  3. Why is a 1 written next to the 2 from \(9-7\)?

Problem 3

Han's calculation of \(972 \div 9\) is shown here.

Student work of division problem.
  1. Find \(180 \boldcdot 9\).
  2. Use your calculation of \(180 \boldcdot 9\) to explain how you know Han has made a mistake.
  3. Identify and correct Han’s mistake.

Problem 4

Find each quotient.

Three long divisions, a, b, c. a, 465 divided by 5. b, 924 divided by 12. c, 1,107 divided by 3.

 

Problem 5

One ounce of a yogurt contains of 1.2 grams of sugar. How many grams of sugar are in 14.25 ounces of yogurt?

A:

0.171 grams

B:

1.71 grams

C:

17.1 grams

D:

171 grams

(From Unit 5, Lesson 7.)

Problem 6

The mass of one coin is 16.718 grams. The mass of a second coin is 27.22 grams. How much greater is the mass of the second coin than the first? Show your reasoning.

(From Unit 5, Lesson 4.)