Find the product of 21 and (6.3 • 10^-4).

0.1323 • 10^-1
1.323 • 10^-3
1.323 • 10^-2
1.323 • 10^2

Question

Find the product of 21 and (6.3 • 10^-4).

0.1323 • 10^-1
1.323 • 10^-3
1.323 • 10^-2
1.323 • 10^2

mrnood · Answer

first multiply 21 * 6.3

and write it in the exponent form

post you answer here

anonymous · Answer

132.3

mrnood · Answer

can you write that in 'exponent form ?

like 1.56 * 10^2

anonymous · Answer

Is it 132.3 * 10^0?

mrnood · Answer

that is one way to write it can you write it as 
1.323 * 10^?

anonymous · Answer

is it possible, you're asking?

mrnood · Answer

no - it is possible

can you do it - what is the value of ? so that 132.3 is the same as 1.323 *10^?

anonymous · Answer

I know that you have to move the decimal over two spaces to the left by dividing it by 100. That IS correct, right? XD

mrnood · Answer

yes

132.3= 1.323*100 = 1.323 *10^?

what is the value of ? in the above?

anonymous · Answer

I have no clue. 1.323*100 is 132.3 but that's what we started with...

mrnood · Answer

the point of the exercise is to be able to express numbers in exponent form (or sometimes called scientific notation)

you can see maybe that (for example)

1101 = 110.1 *10^1
1101 = 11.01 * 10^2
1101 = 1.101 * 10^3
1101 = .1101 * 10 ^4

SO using the same idea can you look at

132.3= 1.323*100 = 1.323 *10^?

anonymous · Answer

is it... 1.323 • 10^-3

anonymous · Answer

is it... 1.323 • 10^-3

mrnood · Answer

132.3= 1.323*100 

we are multiplying by 100

how would you write 100 = 10^?

anonymous · Answer

eh... I dont know

mrnood · Answer

Well I'm afaid you are probably not ready to tackle questions like this then.

The key point is that we can move the decimal point where we want - as LONG AS we multiply by 10^? to compensate.

BUT you must know that 
10^0 =1
10^1 = 10
10^2 = 100
10^3 = 1000

etc.

anonymous · Answer

Oh! Oh that makes sense

mrnood · Answer

how would you write 100 = 10^?

anonymous · Answer

100 would be 10^2

mrnood · Answer

OK so lets go back toi the original question

21 *6.3 • 10^-4

you worked out was the same as

132.3 *10^4

which is the same as 
1.323 *10^2  * 10^-4

so what happens when you multiply 2 numbers with exponents?
10^2 * 10^-4  = 10 ^?

anonymous · Answer

When you multiply 2 numbers with exponents dont you add the exponents and if the bases are the same then you keep them as that number? So this would be 10^-2?

mrnood · Answer

excellent - so you have your answer now

anonymous · Answer

Ah! Thank you so much