What if the 2 numbers were switched? How can you even go below zero?

Below zero there would be negative numbers

Can you take away 1/2 of something?

Depends on the item. For example, you can cut a sandwich in half and take one piece.

How far does negative numbers go? Is it like normal numbers? Never ending?

Yes, Negative numbers go on forever just on the other side of the number line.

How would you represent negative numbers?

Negative numbers represent the distance in the opposite direction on the number line. The negative symbol can be seen as a subtraction sign, because 0 - 5= -5.

Why subtraction has this (-) sign?

It is easier to use the (-) sign is stead of saying plus a negative.

who invented subtraction?

Nobody knows but it was found in a book called Mercantile Arithmetic by Robert Recorde

Is it just me or does subtraction take slightly more brain power than addition.

I also agree that subtraction seems more difficult than addition. This is likely because we learned addition *before* we learned subtraction, so since we've known addition *longer*, it may seem easier when compared to subtraction.

What person invented math

No one person invented math, many people contributed to it's development over many, many years.

Main content

Kindergarten

Course: Kindergarten > Unit 2

Lesson 1: What is addition? What is subtraction?

Intro to subtraction

Name: Intro to subtraction
Uploaded: 2014-04-25T19:24:36Z
Description: Sal talks about what it means to subtract. The examples he uses are 4-3 and 5-2.

Google Classroom

Sal talks about what it means to subtract. The examples he uses are 4-3 and 5-2. Created by Sal Khan.

Want to join the conversation?

Sort by:

[Au]^79
Posted 9 years ago. Direct link to [Au]^79's post “What if the 2 numbers wer...”
What if the 2 numbers were switched? How can you even go below zero?
Button navigates to signup pageComment on [Au]^79's post “What if the 2 numbers wer...”
(55 votes)
Answer
- Blueberry
  Posted 3 years ago. Direct link to Blueberry's post “Below zero there would be...”
  Below zero there would be negative numbers
  Comment on Blueberry's post “Below zero there would be...”
  (3 votes)
imange77
Posted 5 years ago. Direct link to imange77's post “How far does negative num...”
How far does negative numbers go? Is it like normal numbers? Never ending?
Button navigates to signup pageComment on imange77's post “How far does negative num...”
(18 votes)
Answer
- Devajsurya
  Posted 5 years ago. Direct link to Devajsurya's post “Yes, Negative numbers go...”
  Yes, Negative numbers go on forever just on the other side of the number line.
  Comment on Devajsurya's post “Yes, Negative numbers go...”
  (15 votes)
Hisha Harb
Posted 5 years ago. Direct link to Hisha Harb's post “Why subtraction has this ...”
Why subtraction has this (-) sign?
Button navigates to signup pageComment on Hisha Harb's post “Why subtraction has this ...”
(10 votes)
Answer
- Michael Bedsaul
  Posted 5 years ago. Direct link to Michael Bedsaul's post “It is easier to use the (...”
  It is easier to use the (-) sign is stead of saying plus a negative.
  Comment on Michael Bedsaul's post “It is easier to use the (...”
  (5 votes)
Dean Howell
Posted 5 years ago. Direct link to Dean Howell's post “Can you take away 1/2 of ...”
Can you take away 1/2 of something?
Button navigates to signup pageComment on Dean Howell's post “Can you take away 1/2 of ...”
(21 votes)
Answer
- pixiehex
  Posted 5 years ago. Direct link to pixiehex's post “Depends on the item. For ...”
  Depends on the item. For example, you can cut a sandwich in half and take one piece.
  Button navigates to signup page
  (2 votes)
sunshineT3
Posted 5 years ago. Direct link to sunshineT3's post “So then it's possible to ...”
So then it's possible to do negative addition?
Button navigates to signup pageComment on sunshineT3's post “So then it's possible to ...”
(14 votes)
Answer
- Edwin Li
  Posted 5 years ago. Direct link to Edwin Li's post “It is possible, because y...”
  It is possible, because you can add a number to a negative number to make it positive or closer to 0.
  Button navigates to signup page
  (1 vote)
🤗😇Corby😇🤗
Posted 6 years ago. Direct link to 🤗😇Corby😇🤗's post “who invented subtraction?”
who invented subtraction?
Button navigates to signup pageComment on 🤗😇Corby😇🤗's post “who invented subtraction?”
(9 votes)
Answer
- Krish Dulal
  Posted 6 years ago. Direct link to Krish Dulal's post “Nobody knows but it was f...”
  Nobody knows but it was found in a book called Mercantile Arithmetic by Robert Recorde
  Comment on Krish Dulal's post “Nobody knows but it was f...”
  (17 votes)
NumerousSeven
Posted 5 years ago. Direct link to NumerousSeven's post “How would you represent n...”
How would you represent negative numbers?
Button navigates to signup pageComment on NumerousSeven's post “How would you represent n...”
(11 votes)
Answer
- Deirdre Moore
  Posted 5 years ago. Direct link to Deirdre Moore's post “Negative numbers represen...”
  Negative numbers represent the distance in the opposite direction on the number line. The negative symbol can be seen as a subtraction sign, because 0 - 5= -5.
  Comment on Deirdre Moore's post “Negative numbers represen...”
  (6 votes)
🤗😇Corby😇🤗
Posted 6 years ago. Direct link to 🤗😇Corby😇🤗's post “What person invented math”
What person invented math
Button navigates to signup pageComment on 🤗😇Corby😇🤗's post “What person invented math”
(6 votes)
Answer
- FunkyChicken
  Posted 6 years ago. Direct link to FunkyChicken's post “No one person invented ma...”
  No one person invented math, many people contributed to it's development over many, many years.
  Comment on FunkyChicken's post “No one person invented ma...”
  (16 votes)
patrick parr
Posted 4 years ago. Direct link to patrick parr's post “how do i learn how to do ...”
how do i learn how to do more easy subtraction cuz i suck at subtraton and im super good at addition.
Button navigates to signup pageComment on patrick parr's post “how do i learn how to do ...”
(9 votes)
Answer
- brycen.dittmer
  Posted 3 months ago. Direct link to brycen.dittmer's post “so count on ur fingers so...”
  so count on ur fingers so lets say the problem is 8-3 u hold up 8 fingers and then take 1 away then u would be at 7 fingers then u keep taking away fingers until u toke away 3 fingers and how many fingers you are holding up is the awnser
  Button navigates to signup page
  (1 vote)
carb0nshel1
Posted 6 years ago. Direct link to carb0nshel1's post “Is it just me or does sub...”
Is it just me or does subtraction take slightly more brain power than addition.
Button navigates to signup pageComment on carb0nshel1's post “Is it just me or does sub...”
(7 votes)
Answer
- Kaden Campbell
  Posted 6 years ago. Direct link to Kaden Campbell's post “I also agree that subtrac...”
  I also agree that subtraction seems more difficult than addition. This is likely because we learned addition before we learned subtraction, so since we've known addition longer, it may seem easier when compared to subtraction.
  Button navigates to signup page
  (6 votes)

Video transcript

Voiceover:Let's explore what it means to subtract numbers. So let's say that I want to figure out what 4, what 4 minus 3 is. 4 minus 3. So one way to think about this, is you start with 4 objects. And so let me just draw 4 objects. So there I have 1, 2, 3, and 4. And when I ... So this is the 4 objects right over here. And when I say minus 3, or if I'm going to subtract 3 from the 4, one way to think about it is, I'm going to take 3 of these 4 objects away. So let's do that. So I'm going to take away 1, I'm going to take away 2, and I'm going to take away 3. Notice, I took away 1, 2, 3 objects. So how many do I have leftover? Well, if I start with 4 and I take away 3, I subtract 3, 4 minus 3, I am left with, I am left with, 1 object, right over here. So 4 minus 3 is equal to, is equal to 1. Fascinating. Let's do another one of these. Let's figure out what 5, what 5, what 5 minus 2 is. And let's write it this way. Let's say we want to figure out something, some question mark, some question mark ... Actually, let me just clear this out. I'll just do it right over here, actually. So let's say we have some question mark. So there's some unknown number right over here. So I'll just put a question mark over here. And we say that unknown number is equal to, is equal to 5, 5 minus 2. Minus 2. Minus 2. So what is this going to be? Well let's visualize it. This means I have 5 things and I'm going to take away 2 of them and this is going to be what I have leftover after I start with 5 and take away 2. So I have 1, 2, 3, 4, 5 things. Now I am going to take away 2 of them. So I'm going to take away 1 and 2. So I took away 1, 2 objects. So how many do I have leftover? Well, I have leftover these, these ... Let me do this in a different color. I have leftover these purple things right over here. So how many is that? How many do I have leftover? Well, I have leftover 1, 2, 3 of my original 5. So something is equal is 5 minus 2. That something is 3. 3 is equal to 5 minus 2. Let me just replace this with a 3. So we see that 3 ... Actually, let me do the 3 in the same color as this green. So we see that 3, 3 is equal to 5 minus 2 or we could say that 5 minus 2 is equal to 3. Either way.