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Activity 1.2 Arithmetic

Introduction

Activity 1.2

Arithmetic

Topics

Arithmetic in programming
The Number data type
Math operators

Any useful program, from video games to online stores, relies on numbers.

Whether it's calculating scores, processing transactions, or generating graphics, math is everywhere in software.

The Number Data Type

In JavaScript, the number type represents both integers and floating-point (decimal) values.

2.5 401 -65 -123.45 1_000_000 "35"

Demo Print Some Numbers

Use the console.log() function to display some numbers on the screen.

1
console.log(-1953);
2
console.log(1_000_000);

Math Operators

+ Addition

- Subtraction

* Multiplication

/ Division: Divides two numbers and returns the quotient as a decimal.

% Modulus (Mod): Divides two numbers and returns the remainder.

Order of Operations

Use parenthesis for operator precedence.

3 * 4 + 5

3 * (4 + 5)

Demo: Print Some Math Expressions

Use console.log() to display the result of some math expressions.

1
console.log(10 * 10.2);
2
console.log(450 / 5);
3
console.log(10 % 3);

'F' → Fullscreen

Objectives

Write Math Expressions
Output numeric values with console.log()
Document code with comments
Practice order of operations

Activity Tasks

Create a new project named 1-2-arithmetic.js.
Complete each task individually.

Task 1: Addition and Subtraction

Display the result of the addition and subtraction expressions using console.log().

1
// Addition
2
console.log("I'm adding 2 and 1. The result is:");
3
console.log(2 + 1);
4
console.log();
5

6
console.log("Adding $1000 and $500.96 gives us:");
7
console.log(1000 + 500.96);
8
console.log();
9

10
// Subtraction
11
console.log("I have 3 apples, and I eat one. Now, I have:");
12
console.log(3 - 1);
13
console.log();
14
//

Task 2: Multiplication and Division

Display the result of the multiplication and division expressions using console.log().

1
// Addition
2
console.log("I'm adding 2 and 1. The result is:");
3
console.log(2 + 1);
4
console.log();
5

6
console.log("Adding $1000 and $500.96 gives us:");
7
console.log(1000 + 500.96);
8
console.log();
9

10
// Subtraction
11
console.log("I have 3 apples, and I eat one. Now, I have:");
12
console.log(3 - 1);
13
console.log();
14

15
// Multiplication
16
console.log("I'm 30 years old. In months, that's: "); // Replace 30 with your age
17
console.log(30 * 12); // Replace 30 with your age
18
console.log();
19

20
// Division - Quotient and remainder
21
console.log("If we divide 8 pizza slices between 2 people, each person gets:");
22
console.log(8 / 2);
23
console.log();
24

25
console.log("Dividing $100 among 6 people gives each person:");
26
console.log(100 / 6);
27
console.log();
28
//

Task 3: Modulo Operation

Use the mod operator to find the remainder portion of the division operation.

1
// Addition
2
console.log("I'm adding 2 and 1. The result is:");
3
console.log(2 + 1);
4
console.log();
5

6
console.log("Adding $1000 and $500.96 gives us:");
7
console.log(1000 + 500.96);
8
console.log();
9

10
// Subtraction
11
console.log("I have 3 apples, and I eat one. Now, I have:");
12
console.log(3 - 1);
13
console.log();
14

15
// Multiplication
16
console.log("I'm 30 years old. In months, that's: "); // Replace 30 with your age
17
console.log(30 * 12); // Replace 30 with your age
18
console.log();
19

20
// Division - Quotient and remainder
21
console.log("If we divide 8 pizza slices between 2 people, each person gets:");
22
console.log(8 / 2);
23
console.log();
24

25
console.log("Dividing $100 among 6 people gives each person:");
26
console.log(100 / 6);
27
console.log();
28

29
// Remainder using the modulus, or mod, operator
30
console.log("After dividing $100 among 6 people, the leftover cents are:");
31
console.log(100 % 6);
32
console.log();
33
//

Task 4: Order of Operations

Use parenthesis to control the order in which the operations are calculated.

1
// Addition
2
console.log("I'm adding 2 and 1. The result is:");
3
console.log(2 + 1);
4
console.log();
5

6
console.log("Adding $1000 and $500.96 gives us:");
7
console.log(1000 + 500.96);
8
console.log();
9

10
// Subtraction
11
console.log("I have 3 apples, and I eat one. Now, I have:");
12
console.log(3 - 1);
13
console.log();
14

15
// Multiplication
16
console.log("I'm 30 years old. In months, that's: "); // Replace 30 with your age
17
console.log(30 * 12); // Replace 30 with your age
18
console.log();
19

20
// Division - Quotient and remainder
21
console.log("If we divide 8 pizza slices between 2 people, each person gets:");
22
console.log(8 / 2);
23
console.log();
24

25
console.log("Dividing $100 among 6 people gives each person:");
26
console.log(100 / 6);
27
console.log();
28

29
// Remainder using the modulus, or mod, operator
30
console.log("After dividing $100 among 6 people, the leftover cents are:");
31
console.log(100 % 6);
32
console.log();
33

34
// Order of operations
35
console.log("The expression 4 * 10 + 12 equals:");
36
console.log(4 * 10 + 12);
37
console.log("The expression 4 * (10 + 12); equals:");
38
console.log(4 * (10 + 12));
39
//

Sample Output

Your program output should something similar to the sample output below.

I'm adding 2 and 1. The result is:
3

Adding $1000 and $500.96 gives us:
1500.96

I have 3 apples, and I eat one. Now, I have:
2

I'm 30 years old. In months, that's:
360

If we divide 8 pizza slices between 2 people, each person gets:
4

Dividing $100 among 6 people gives each person:
16.666666666666668

After dividing $100 among 6 people, the leftover cents are:
4

The expression 4 * 10 + 12 equals:
52
The expression 4 * (10 + 12); equals:
88

Reflection Questions

You may write your reflection answers as comments at the bottom of your code.

How did the use of parentheses change the result in the order of operations example? Why is that important when writing code?
Which math operator did you find most surprising or unfamiliar in JavaScript, and why?
Why is it helpful to include spaces around math operators (like +, -, *, /) when writing code, even though JavaScript works without them?

Submission

Submit your activity and reflection answers to the appropriate dropbox.