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Lesson 1: Writing expressions

# Evaluating expressions with & without parentheses

Explore the concept of order of operations, emphasizing the importance of parentheses in mathematical expressions.Learn how the placement of parentheses can drastically change the outcome of an expression, highlighting the need to follow the correct sequence: parentheses, multiplication and division, then addition and subtraction. Created by Sal Khan.

## Want to join the conversation?

• why does the math seem easier in the videos than in reality
• Because the people who makes the videos know how to do math really good.
• plz give me a vote so i can get a badge
• can you please show more examples because those two were helpful and i did understand it but it is still pretty confusing
• I don't know
• Doesn't a negative plus a negative equal a positive number.
• A negative plus a negative will always equal a negative because you are taking a value less than zero and "applying more negativity to it" For example, you are already underground, and adding a negative distance means you will be digging even deeper underground.
However, a negative times a negative will become positive.
• what if there is two perethisis and that's what I don't get and what I mean is witch one should I do first if you know lease explain it to me thanks so much!
(1 vote)
• In the example equation:
(10 × 4) + (4 ÷ 2)
You must solve the parenthesis first (Moving left to right)
(10 × 4 = 40) + (4 ÷ 2)
40 + (4 ÷ 2 = 2)
40 + 2 = 42

In this other example parentheses inside of parentheses:
((10 × (4 ÷ 2)) × 2) + 2
You solve the most nested parentheses first.
((10 × (4 ÷ 2 = 2)) × 2) + 2
((10 × 2 = 20) × 2) + 2
(20 × 2 = 40) + 2
40 + 2 = 42

Did this help? If so, great! If not, explain to me what you still don't understand.
• What's the difference between parentheses(), curly brackets{}, and brackets[]?
• Parentheses () are used to group numbers or expressions that you want to calculate first. For example, in 2 + (3 × 4), you do 3 × 4 first because it is inside the parentheses.
Curly brackets {} are used to show sets of numbers or objects. A set is a collection of things that have something in common. For example, {1, 2, 3} is a set of three numbers.
Brackets [] are basically only used when you have more than one pair of parentheses in an expression. You use them outside the parentheses to show what to do next. For example, in [2 + (3 × 4)] ÷ 5 , you do 2 + (3 × 4) first because it is inside the brackets.

In a complicated expression, all three can be used, in this order: parentheses first, then brackets, then curly brackets. For example:

4 - 3 [4 - 2 {6 - (5 + 1)}] ÷ 3
First: 4 -3 [4 -2 {6 - 6}] ÷ 3
Then: 4 -3 [4 -2 × 0] ÷ 3
Then: 4 - 3 × 4 ÷ 3
Then: -8 ÷ 3
So the answer is -8 divided by 3.
• I have a Quick Questions how bo you do that
• 1-(4-2x12)+7 in that problem,inside the parentheses, do i do the multiplication first, or the subtraction?