Unit 4 Contents

Check-In: Question 14–15

14. Solve the following problems.
• Decide whether you need an exact answer or an estimate.
• Then, decide whether you can solve it in your head or whether you will need paper and pencil. If you use paper and pencil, show your work.
• If you use mental math, be ready to explain how you solved it.
1. There are 22 students in Mrs. Dewey's class. Ming plans to bring cookies to class on his birthday. He wants to be sure that everyone gets the same number of cookies. If he brings five cookies for each student, how many should he bring?

2. Nicholas is laying tile in a hallway. The hall will have 7 rows of tiles with 86 tiles in each row. How many tiles does he need?
3. Maya is buying school supplies. She has $3.00. Erasers are 58¢ each. Does she have enough money to buy 5 erasers? Show or tell how you know.

4. Maya buys 4 pads of paper that cost 99¢ each. If she pays with a $5 bill how much change will she receive?
15. Choose a problem from Question 14 that you can solve using mental math. Show or tell what was “in your head.”

Complete the What Were They Thinking pages in your Student Activity Book for more multiplication practice.

For the problems below, do as much work in your head as you can. Use methods like Jerome's, Tanya's, Nila's, Sara's, or one of your own.

1. At Raye School, there are 3 fourth-grade classes. If there are 26 students in each class, how many fourth-graders are there at the school?
2. The parking lot at a shopping center has five rows for cars to park. Each row has spaces for 98 cars. How many cars can park in the lot?
3. January, March, May, and July each have 31 days. How many days are in all four months together?
4. Between three and five students in Mrs. Dewey's class are absent each day in January and February. Estimate the total number of absences in the two months.
5. There are 52 cards in one deck of cards. How many cards are in six decks?