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### Course: Arithmetic (all content)>Unit 3

Lesson 1: Multiplication intro

# More ways to multiply

Sal uses arrays and repeated addition to multiply.  Created by Sal Khan.

## Want to join the conversation?

• hi sal, ive learnt soo much from you, I'm not that good with math but after joining khan academy I know how to multiply 10s, 100s, ect. add, subtract, and decimals, but I am really struggling to memorise the multiplication table, any tips?
• well write it down a few times that is how i learned it.
• What if you have 0 group
• Its just 0 because that is kind of like a 0
• can anyone multiply 10000x10000?
• It's 100,000,000/100 million because we have 10000 groups of 10000
• what if you don't know how to skip count by 8 than what do you do?
• Remember that 8 is the same as 2 groups of 4. (8 = 2 x 4) If you can't count by groups of 8, try counting by groups of 4. If that is still too hard, try counting by groups of 2 and work your way up to counting by larger numbers.
• hi do you guys understand how mutiplication and division are alike?
• can someone help me with multiplying by 8
• There are some good tricks for multiplying by 8. Here are two of them.

1) Multiply by 10, then subtract twice the original number.

2) Double, double, and double.

Example: let’s do 6 x 8 using each trick.

Trick 1): 10 x 6 = 60.
2 x 6 = 12.
60 - 12 = 48.

Trick 2): Double 6 is 12.
Double 12 is 24.
Double 24 is 48.

Have a good day!
• If you are not dume what is 111,9999x 12,99999
• I am not bumd(: