How to button pants with 1 hand
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Lay down on a bed if pants are tight. Suck in the gut if needed.
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Start the zipping process.
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Zipping right along!
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Zip up as much as you can to make the button to hole distance as small as possible.
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Start by putting your index finger through the button hole (from out side towards inside) about 1/2 way up the nail. If your index finger is too big you can use a little finger but it takes more practice.
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Thumb goes against the far edge of the button.
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Pull button past tip of finger and exchange finger tip position for thumb postion on the far edge of the button. (still through the hole)
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Now the edge of the button should be aimed up towards the largest part of the button hole at an angle.
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Work thumb behind waist band behind the low edge of the button and push the button aginst the finger tip till you push your finger out of the hole with the button.
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Pictures courtesy of Tom.