# Lesson 12 Solve Problems Involving Multiplication

Let’s solve problems using what we learned about multiplication of whole numbers.

## Warm-up What Do You Know About …?

What do you know about 1 year?

## Activity 1 Time Flies When We Leap Years

A baby elephant was born exactly 48 weeks ago. How many days old is she?

A leap year has 366 days. A non-leap year (or a common year) has 365 days. How many days are in 3 leap years?

In our calendar system, some months are 31 days long, some are 30 days long, and one month (February) is either 28 or 29 days long.

What if the calendar system changed so that each month has 31 days? How many more days would there be in a year?

## Activity 2 Coin Collection

Lin’s family has collected 2,074 nickels over the years. How many pennies are worth the same amount?

If Lin’s family saved 2,074 nickels each year for 4 years, how many nickels would her family have?

Create a situation that involves a problem that can be solved by finding the value of

. Solve the problem and show your reasoning.

## Practice Problem

## Problem 1

There are 4,218 students in school district A. School district B has 3 times as many students as school district A. How many students are in school district B? Explain or show your reasoning.