Computer Science
Grade 5
20 min
Using Formulas: Multiply and Divide
Students will expand their knowledge of formulas to include multiplication and division.
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1
Introduction & Learning Objectives
Learning Objectives
Translate a real-world multiplication problem into a computer formula using the '*' operator.
Translate a real-world division problem into a computer formula using the '/' operator.
Store the result of a multiplication or division formula in a variable.
Combine multiplication and division operators in a single expression to solve a multi-step problem.
Use parentheses '()' to control the order of operations in a formula.
Explain how computers use formulas to perform calculations for tasks like scoring in games or resizing images.
Ever wonder how a game instantly knows your new score when you collect 5 coins worth 10 points each? 🎮 It's not magic, it's a multiplication formula!
In this lesson, we will learn how to w...
2
Key Concepts & Vocabulary
TermDefinitionExample
FormulaA step-by-step instruction written for a computer to solve a problem, much like a recipe. It uses variables, numbers, and operators.In code, a formula to find the total points from 5 coins worth 10 points each would be `total_points = 5 * 10`.
OperatorA special symbol that tells the computer to perform a specific math action.The `*` symbol is the multiplication operator, and the `/` symbol is the division operator.
OperandThe values (numbers or variables) that an operator works on.In the formula `100 / 5`, the numbers `100` and `5` are the operands.
VariableA named container in your code that stores a value, like a number or text. The value inside can change.`let score = 0;` creates a variable named `score` and gives it an initial value of 0.
ExpressionA combi...
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Core Syntax & Patterns
Multiplication Formula
result = value1 * value2
To multiply in code, use the asterisk `*` symbol (Shift + 8 on most keyboards). Place it between the two numbers or variables you want to multiply. The answer is often stored in a variable using the assignment operator `=`.
Division Formula
result = value1 / value2
To divide in code, use the forward slash `/` symbol. The number on the left is divided by the number on the right. Be careful not to divide by zero, as this will cause an error!
Order of Operations (PEMDAS)
1. Parentheses `()` 2. Exponents 3. Multiplication `*` and Division `/` (from left to right) 4. Addition `+` and Subtraction `-` (from left to right)
Computers follow a strict order when solving math problems. If you want to force a certain part of your...
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Challenging
A student writes `let answer = 100 / 10 * 2;`. They expected the answer to be 5 (by doing 10 * 2 first), but the computer calculated 20. Why did the computer get 20?
A.Multiplication always happens before division.
B.The computer calculated from left to right because division and multiplication have equal priority.
C.The computer made a mistake; the answer should be 5.
D.Parentheses should have been used like this: `100 / (10 * 2)` to get 5.
Challenging
In the 'Pizza Party Planner' example, imagine the number of people doubles to 16, but a coupon halves the `cost_per_pizza` to $8. What is the new `total_cost`?
A.$128
B.$16
C.$32
D.$64
Challenging
You have 25 cookies to share among 4 friends. Using multiplication and division, how could you write a formula to find out how many cookies are LEFT OVER after giving each friend an equal amount?
A.let leftovers = 25 / 4;
B.let leftovers = (25 * 4) - 25;
C.let leftovers = 4 * 6;
D.let leftovers = 25 - (4 * 6);
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