# The Missing Dollar

## Curriculum Expectations

Number Sense 8m23 Evaluate expressions that involve integers, including expressions that contain brackets [...] using order of operations.

## Problem

Transcript: These three stick men were having lunch in a restaurant. The bill came out to $30, so they each put in$10 (since $latex \$10 \times 3 = \$30$ total).

The cashier realizes that they've been overcharged $5, so he gives$5 back to the waitress to give to the men. But since $5 can't be divided equally, she decides to just give the men back$1 each, and keep $2 for herself. So that means each man paid$latex \$10 - \$1 = \$9$.

All three men paid $latex 3 \times (10 - 1) = \$27$in total. Since the waitress kept$2, and the men paid $27, you get$latex 3 \times (10 - 1) + 2 = \$29$.

https://youtu.be/9iJdQf6t5_g?t=11s

1. What happened to the extra dollar?

## Solving

2. Students can use any type of manipulatives they like to solve the problem. Have a variety of manipulatives to choose from.

## Solution

https://youtu.be/Rgh21N3O7tM

## Student Exemplars

The following exemplars are all somewhere in a level 4, which as a percentage means something between 80% and 100%.

Here is the original Exit Ticket (evaluation) as a Word document: 2015-11-10 Chapter 1 Number Relationships The Missing Dollar Problem

Student Exemplar 1

Student Exemplar 2

Student Exemplar 3