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### Unit 1: Lesson 1

Sal adds 8 + 7 by making a group of ten. Created by Sal Khan.

## Want to join the conversation?

• What is the importance of Adding?
• Math is a way to analyze complex problems and the world around you. It helps your brain connect pathways and come to quicker solutions by breaking down a problem to its most basic ingredients (first principle thinking). It's only when you're able to break down a problem to its most fundamental components, you're able to see the solution. In math, we do this by using an abstract language (numbers)

Example:
8 + 7
10-8=2
7-2=5
10+5=15
• I'm just here to study for my test even I'm in 5th grade XD my math teacher keeps say STUDY FOR TEST! I'm like srsly ;-;
<3
• I have eight bears. I gave some to Clara. Now I have 4 bears. How many did I give away?
• you now have 4 dangerous bears
• Is 7+3+5 an equation that can be used to get 7+8?
• That's another way of looking at it, yes. You could start at 7+3+5, then go (7+3)+5 so that you get 10+5, which equals 15. You could also go the other way with it, 5+2+8 -> 5+(2+8) -> 5+10 = 15.
• what would be 20 plus 900 plus 150
• Work it out: start with 900 + 150 = 1050. 1050 + 20 = 1070
• why do we need to learn this... i mean isn't having fingers is to count?
please explain i feel like i am 6 years old
• Well, it will become useful later in life. Try using your fingers to add 65,465+56,349
• So I'm a little bit confused about common core. What has changed, and how can I help my brother with it? Is there good information somewhere? Their website seems rather vague.