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# 25 mm wide x 40 mm length what's that in inches?

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25 mm wide x 40 mm length what's that in inches?

Guest Jul 28, 2017

#1
+1221
+2

To convert from millimeters to inches in 2 dimensions, you must convert both the width and length before multiplying. I happen to only know this conversion from memorization:

$$1in=0.0254m$$

Of course, we want to go from millimeters to inches, so I must change the meters to millimeters. That is relatively simple:

 $$\frac{1000mm}{1m}=\frac{xmm}{0.0254m}$$ Using this proportion, we can figure out how many millimeters are in 0.0254 meters. $$x=0.0254*1000=25.4mm$$

Ok, so now we know information that is a tad more useful than before.

$$1in=25.4mm$$

Using this knowledge, we can now convert both dimensions: 25mm and 40mm.

 $$\frac{1in}{25.4mm}=\frac{xin}{25mm}$$ Cross multiply to solve this proportion for x. $$25=25.4x$$ Divide by 25.4 on both sides. $$x=\frac{25}{25.4}*\frac{10}{10}$$ I, personally, do not like seeing decimals in fractions, so I am manipulating the fraction such that one exist. $$x=\frac{250}{254}=\frac{125}{127}in$$ For now, I will leave the fraction in this form/

Now I will convert 40mm into inches:

 $$\frac{1in}{25.4mm}=\frac{yin}{40mm}$$ Cross multiply to solve this proportion for y. I changed the variable so that it would not be confusing. $$40=25.4y$$ Divide by 25.4 on both sides. $$y=\frac{40}{25.4}*\frac{10}{10}$$ Yet again, I am getting decimals out of the fraction. $$y=\frac{400}{254}=\frac{200}{127}in$$

Ok, now multiply both of these fractions together.

$$\frac{125}{127}*\frac{200}{127}=\frac{25000}{16129}in^2$$

Unfortunately, this fraction is irreducible

$$\frac{25000}{16129}in^2\approx1.5500in^2$$

TheXSquaredFactor  Jul 29, 2017
Sort:

#1
+1221
+2

To convert from millimeters to inches in 2 dimensions, you must convert both the width and length before multiplying. I happen to only know this conversion from memorization:

$$1in=0.0254m$$

Of course, we want to go from millimeters to inches, so I must change the meters to millimeters. That is relatively simple:

 $$\frac{1000mm}{1m}=\frac{xmm}{0.0254m}$$ Using this proportion, we can figure out how many millimeters are in 0.0254 meters. $$x=0.0254*1000=25.4mm$$

Ok, so now we know information that is a tad more useful than before.

$$1in=25.4mm$$

Using this knowledge, we can now convert both dimensions: 25mm and 40mm.

 $$\frac{1in}{25.4mm}=\frac{xin}{25mm}$$ Cross multiply to solve this proportion for x. $$25=25.4x$$ Divide by 25.4 on both sides. $$x=\frac{25}{25.4}*\frac{10}{10}$$ I, personally, do not like seeing decimals in fractions, so I am manipulating the fraction such that one exist. $$x=\frac{250}{254}=\frac{125}{127}in$$ For now, I will leave the fraction in this form/

Now I will convert 40mm into inches:

 $$\frac{1in}{25.4mm}=\frac{yin}{40mm}$$ Cross multiply to solve this proportion for y. I changed the variable so that it would not be confusing. $$40=25.4y$$ Divide by 25.4 on both sides. $$y=\frac{40}{25.4}*\frac{10}{10}$$ Yet again, I am getting decimals out of the fraction. $$y=\frac{400}{254}=\frac{200}{127}in$$

Ok, now multiply both of these fractions together.

$$\frac{125}{127}*\frac{200}{127}=\frac{25000}{16129}in^2$$

Unfortunately, this fraction is irreducible

$$\frac{25000}{16129}in^2\approx1.5500in^2$$

TheXSquaredFactor  Jul 29, 2017

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