## anonymous one year ago When converting a measurement in cm to a measurement in km. For example 20.7 cm when I switch that to decimeters its 2.07 dm then .207 m. Then deka meter .0207 then hecto .00207 then kilometer .000207 km 2.07e-4 km However my book says its 2.07e-9 km. How is that happening? What am I missing?

1. anonymous

You are correct according to your post. You sure the problem is not asking you to convert $20.7cm^2 \to km^2$

2. anonymous

That is what its asking. lol I figured that the squared didn't matter. Seeing as both are squared I thought I could deal with the numbers independently.

3. anonymous

So im guessing that the squared has something to do with why im confused but what about it being squared changes my answer?

4. anonymous

cm2=(cm)(cm) and km2=(km)(km) Start with given variable and units Solve for the unknown units. Try to make the starting units cancel out by multiplying the cm in denominator twice. You want km^2 so multiply the km twice by putting it as a numerator over the cm. So it equals to this $\frac{ 20.7cm^2 }{ 1 }\times \frac{ ?km }{ 1cm }\times \frac{ ?km }{ 1cm }$ Fraction and numerator should equal after starting out the given variable. Since 0.00001km=1cm then it $\frac{ 20.7cm^2 }{ 1 }\times \frac{ 0.0001km }{ cm }\times \frac{0.0001km }{ cm }$ Multiply it and the cm units would cancel out leaving you with just the km^2 and it would be 0.000000000207km or 2.07 x 10^-9km or 2.07e^-9

5. anonymous

20.7 * 0.0001 * 0.0001 = 0.000000207 = 2.07e-7 How am I still missing this?

6. anonymous

I made a typo, supposed to be 20.7km*0.00001km*0.00001km= I made no typo explaining,just in the conversion example.