A recent example for me. I was making a bag with a round base that was 10cm in diameter from my scrap fabric pile. straight away I knew that the length of fabric I needed for the sides would be 31.4cm plus 1cm for hem allowance. I didn’t have to measure the circumference of the base to know that. (circumference = diameter x 3.14) Straight away I could reject any fabric that was shorter than a foot without wasting any fabric scraps that were longer.
I’ve also used Pi to work our the volume of containers and to give an estimate of the amount of concrete I need to fill post holes.
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