Question

You are fitting a new kitchen and measure the folllowing lengths of pipe.

Answer 1

we know that

$1$ meter is equal to $100$ centimeters

Step $1$

convert all measurements to centimeters

case 1) $0.81\ m$

$0.81\ m = 0.81*100= 81\ cm$

case 2) $1.08\ m$

$1.08\ m = 1.08*100= 108\ cm$

case 3) $0.8\ m$

$0.8\ m = 0.8*100= 80\ cm$

case 4) $180\ cm$

case 5) $18\ cm$

Step $2$

Compare the values

we have

$[81,108,80,180,18]$

the shortest length is $18$

the longest length is $180$

Step $3$

Subtract the shortest length from the longest

$180\ cm-18\ cm=162\ cm$

therefore

the answer is

$162\ cm$

Answer 2

Ok.
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Let's get to some kitchen work!!
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Kitchen designing also takes math skillz.
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So, let's place the numbers we have been given in order!!
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Let's see...
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0.8 meters comes as the shortest.
0.81 meters comes as second shortest. 
1.08 meters -
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WAIT!!
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DON'T GO ON!!
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Centimeters. 180 and 18 centimeters. CENTIMETERS!!
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Gotta make this clear.
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How many centimeters goes into one meter?
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Yup. 100.
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18/100...
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0/18 meters.
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180/100...
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1.8 meters.
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Let's get to work again!!
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18 centimeters comes shortest.
0.8 meters comes 2nd shortest.
0.81 meters comes 3rd shortest.
1.08 meters comes 2nd longest.
180 centimeters comes longest.
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We have everything in place and ready to go!!
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What's 180 - 18?
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162.
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So, the longest minus shortest length pipes have a difference of 162 centimers.
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Hope I helped!!