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### Course: Pre-algebra>Unit 11

Lesson 8: Scientific notation word problems

# Scientific notation word problem: speed of light

It is possible to simplify multiplication and division using scientific notation. This can be used to calculate the distance between the sun and the earth, which is 1.5 times 10 to the 11th power meters. This is an incredibly large distance and difficult to visualize. Scientific notation can be used to simplify calculations and understand large numbers. This involves using the commutative property to rearrange the numbers and multiplying the units, and then adding the exponents to simplify the equation. Created by Sal Khan and Monterey Institute for Technology and Education.

## Want to join the conversation?

• When are we actually ever going to need this in the real world
• If you want to be a scientist, you might want to learn this.
• Hello, I'm not from the US and in my country we don't include units in the computation, only the the result's unit when giving the answer.
Do you always include them in computation? Thanks in advance to whoever answers.
• Yes, you do. I'm not from the US, either.
• Is that THE ACTUAL RATE for the SPEED OF LIGHT?
• Yes, that is the actual speed of light in a vacuum. The speed of light is very close to this value in air.

Have a blessed, wonderful day!
• So what about when you are dividing in scientific notation, how do you know which number goes on top? I have 9 x 10^-5 and 3 x 10^-6. Do i put the one with the highest exponent on top or the biggest number. 9 x 10^-5 would go on top right? thanks
• It depends on what the situation or problem is. It is completely legal within the laws of mathematics to do a/b or b/a, but they yield different quotients. If the problem asks you divide 9*10^-5 by 3*10^-6, then the 9*10^-5 would be on top (or, it would be the numerator). Consequently, if the problem asks you to divide 3*10^-6 by 9*10^-5, 3*10^-6 would be on top.
Correct me if I am wrong or if this answer is confusing.
• I don't wanna be a scientist
• Please choose a career that suits you, something that you like to do! If you don't want to be a scientist, you don't have to be one! :)
(1 vote)
• At how do the seconds cancel out?
• It cancels out because when it was m/s and s it cross cancel or cross reduce which is when u take the 2 numbers/variables diagonal from each other and reduce them but in this instance it is the same so they take each other out
• Sal using the sketch app has inspired me to use it when ever I am doing math.
"Always work out your problems on paper or online that is how you will learn and fully understand."
• Anyone else getting Star Wars vibes when talking about the speed of light? or am i the only one please let me know lol.
• Yes uuu yes