About this video
Sal divides 5.005 by 7 using ordinary long division. The key move is placing the decimal point in the answer directly above the decimal point in 5.005, then dividing digit by digit to get 0.715.
You'll be able to
- divide a decimal by a whole number using long division.
- place the decimal point in the quotient directly above the decimal in the dividend.
- check a decimal quotient by multiplying it back.
Key words
- long division
- A step-by-step way to divide: divide, multiply, subtract, then bring down the next digit.
- decimal point
- The dot that separates the ones place from the tenths, hundredths and smaller places.
- ones place
- The place just to the left of the decimal point.
Transcript
Let's see if we can divide 5.005 by-- let's divide it by 7, and see what we get. So we can rewrite this as 5.005 divided by 7. And the key here is to keep track of the decimal. But other than that, you're really treating it like a traditional long division problem.
So you want to put the decimal, it's to the right of the ones place. So it's right over there. I just put the decimal right above the decimal. And now we would treat it just like a traditional long division problem. So how many times does 7 go into 5? Well, it goes into 5 zero times, and we could write 0 times 7 is 0.
Actually, let's do that, just to show that it works to kind of do the process all the way through. 0 times 7 is 0. You subtract, you get 5. So you get this 5 right over here. So you get 5, and then we can bring down another 0. We bring down this 0 right over here.
So now we ask ourselves, how many times does 7 go into 50? Well, 7 times 7 is 49, so it's going to go seven times. 7 times 7, 49. Subtract, you get 1. And now we can bring down this 0. Let's do that. We bring down that 0. 7 goes into 10 one time. 1 times 7 is 7.
Subtract, get a 3. And now finally, we can bring down this 5. We can bring down the 5. And we ask ourselves, how many times does 7 go into 35? Well, 5 times 7 is 35. This goes 5 times. 5 times 7 is 35. Subtract, and we are done. We have divided it completely. And so 5.005 divided by 7 is equal to 0.715.
Video © Khan Academy, used under CC BY-NC-SA. Watch on Khan Academy. Puzzicle is not affiliated with Khan Academy.