Main content

## Early math review

### Unit 2: Lesson 1

What is addition? What is subtraction?# Intro to addition

Learn what it means to add. The examples used are 1+1 and 2+3. Created by Sal Khan.

## Want to join the conversation?

- Who actually created the idea of fractions,because they are like so helpful?(46 votes)
- Fractions were invented more than likely by the Egyptians to organize taxes on land.(59 votes)

- who actually made addition? like as in, who invented addition?(1 vote)
- The process of addition was first thought of by the Chinese a long, long, long time ago!

They used something called an abacus to add things up, because the addition sign was not created until 1544.(118 votes)

- At0:04, Sal mentions adding numbers. How was this invented, and how were the numbers to add stuff invented?(11 votes)
- Adding numbers was most likely founded from Greek Philosophy, same as the numbers. Great question!(7 votes)

- Where did the symbols for additional (+) and subtraction (-) come from?(3 votes)
- The plus and minus signs (+ and −) are mathematical symbols used to represent the notions of positive and negative as well as the operations of addition and subtraction. Nicole Oresme's manuscripts from the 14th century show the earliest uses of the plus sign (+). The − may be derived from a tilde written over m when used to indicate subtraction, or it may come from a shorthand version of the letter m itself. The alphabet 'm' was used as the minus sign in the Europe until these symbols were intoduced(19 votes)

- Which one is easier subtraction or addition?(5 votes)
- Personally addition but they are both farily easy.(8 votes)

- How would you add in different number bases?(4 votes)
- That is a really good question. The grade level for counting in different bases is like algebra, but I can give u a link to it

https://www.khanacademy.org/math/algebra-home/alg-intro-to-algebra/algebra-alternate-number-bases/v/number-systems-introduction

https://www.khanacademy.org/math/algebra-home/alg-intro-to-algebra/algebra-alternate-number-bases/v/hexadecimal-number-system

https://www.khanacademy.org/math/algebra-home/alg-intro-to-algebra/algebra-alternate-number-bases/v/decimal-to-binary

https://www.khanacademy.org/math/algebra-home/alg-intro-to-algebra/algebra-alternate-number-bases/v/large-number-decimal-to-binary

https://www.khanacademy.org/math/algebra-home/alg-intro-to-algebra/algebra-alternate-number-bases/v/binary-addition

https://www.khanacademy.org/math/algebra-home/alg-intro-to-algebra/algebra-alternate-number-bases/v/binary-multiplication

This is all in algebra! Hope this answers your question!!(5 votes)

- how many numbers can you add at the same time?(3 votes)
- You can add as many numbers at once as you want.(6 votes)

- How is addition like counting?(4 votes)
- When counting you are adding by 1.

For example, when counting 1, 2, 3, 4, 5, etc., you can represent every number as an addition: 1, 1+1, 1+1+1, 1+1+1+1, 1+1+1+1+1, etc.(1 vote)

- how can addition help use in real life.(3 votes)
- Math is around us. Addition is always being used!(1 vote)

- Well, at0:55if that's how addition works, then what is 1,007,458 + 76,943?(3 votes)

## Video transcript

Voiceover:Let's think about what it means to add numbers. So let's start with 1. 1 plus. 1 plus 1. What is this going to be equal to? One way to think about this is we have 1 thing, and that thing
will be a purple circle. So let me put that here. So that's this 1 thing. I'm just going to represent it with a purple circle. And I'm going to add another 1 thing. And since this is in blue, I'll make that other circle, I'll
make that in blue as well. So let me put that right over here. So 1 plus 1. 1 plus 1. How many total circles do I now have? Well, I now have 2 circles. I now have 2 circles. 1 plus 1 is equal to, is equal to 2. Okay, you're saying all
right Sal, all right, that makes sense. Let's do this with larger numbers. So let's say we want
to know what equals ... And I'll put a question mark over here. So, question mark. What equals ... So something is equal to, is equal to, let's say, 2, 2, 2 plus 3. Something is equal to 2 plus 3. What is this something going to be? I encourage you to pause
the video and think about it on your own. Well, you could view
this as, I have 2 objects and then we're going to
add another 3 objects. How many total objects would I have? So you have your 2 objects, which I'll use purple circles again. So let me ... Let me, so, we have 1
and 2 purple circles. This is the 2 right over here. And then to that we're
going to add 3 more. 3 more circles. I'll represent those in blue because we wrote the 3, here, in blue. So that is 1, 2, and 3. So how many total circles do we now have? Well, we could count them. We have 1, 2, 3, 4, 5. In fact, let me count that. 1, 2, 3, 4, 5 circles. So 2 plus 3. 2 things plus another
3 things are 5 things. So our question mark, right over here, is equal to 5. So instead of writing the question mark right over here, let me clear that out. I could say 5 is equal to. I could write down that
5 is equal to 2 plus 3.