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### Course: Kindergarten>Unit 2

Lesson 1: What is addition? What is subtraction?

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

## Want to join the conversation?

• Where did the symbols for additional (+) and subtraction (-) come from?
• 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
• 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.
• Which one is easier subtraction or addition?
• Personally addition but they are both farily easy.
• how many numbers can you add at the same time?
• You can add as many numbers at once as you want.
• How would you add in different number bases?
• How is addition like counting?
• do you have a quick way too do 10+24+9+8+12+4+56
• Yes, there are plenty of tricks.
1) In 10+24+9+8+12+4+56 find groups of ten(s) first. For example, add 4+56, and that will get you 60. If you are doing it on paper, you can cross out 4+56 and write "60" above it. Do that for other numbers, such as 8+12 = 20. when you do all of them, add the ones that do not make a group of 10 or more. Add those, to the groups of ten, and you got the answer.

2) Since this is addition, you can rearrange the numbers in an order that is easier to calculate, for example, 12+8+56+4+10+24+9.

3) Use a calculator (but sometimes thats cheating
• If you add a negative and a positive, is it the same as subtraction?
• Yes. Think of it like you have 3 dollars, but you are in debt of your mother for 2 dollars. You would be adding 3 to 2 dollars of debt, which is the same as 3-2. Hope this helped!
• Can You Do Triple Addition Like 9 + 10 + 2 =21?