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### Course: 4th grade (2018 edition)>Unit 2

Lesson 3: Multi-digit multiplication: standard algorithm

# Multiplying: 2-digit by 1-digit (regrouping)

Sal solves 6x37. Created by Sal Khan.

## Want to join the conversation?

• So at , the ansewr is 222?
• show 390*8*7 390 8 times 7=
• The only thing I want to know is how to do a problem like this:
It has two large numbers and a smaller one that could equal to a very large number like those I am battling on CTC Math, is there any advice?
• That is true Nicolas but what if you had let's say 3678 x 57? That would be a little harder than doing the typical way, this is building onto harder and harder equations, hope this helps! :)
• how do u multiply 9 digit #"s
• ok so say you have 9x7 right! you would subtract 1 from seven which is six and you count from six till you get to nine. so how much do you count to get from six to nine? you get 3........EX. 6,7,8,9. you put the 6 and the three together and you have 63 and this method is for all number not just this one! I REALLY HOPE THE HELPED YOU!
(1 vote)
• How do you multiply 3 digit numbers
(1 vote)
• Y is my videos not working
(1 vote)
• How would this be useful in the real world
(1 vote)
• If you have a rectangle 11 inches wide, and 3 inches tall, and need to figure out how much carpet you would need to buy to fill this rectangle, you are able to calculate...
11*3= 33 you would need to but 33 square inches of carpet.
(1 vote)
• At does that mean you can change it around for every operation?
(1 vote)
• No. It only works for multiplication and addition because they are commutative. Communitive means that no matter where your numbers are, you get the same answer.