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A comment on A mathematician's way of converting miles to kilometers. Parent comment

Re:A mathematician's way of converting miles to kilometers by skykooler on Saturday August 10, 2019 @01:06PM (#20663220)
For inches to cm in my head, I multiply by 10 and then divide by 2 twice. E.g. 7 inches -> 70 -> 35 -> ~17.5 cm.
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Re:A mathematician's way of converting miles to kilometers by frosas on Sunday August 11, 2019 @01:50AM (#20666496)
I do something similar but, because I'm faster at multiplying, I do "its double plus its half". E.g. 7 inches = 14 + 3.5 = 17.5 cm
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