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Old 08-05-2009, 03:16 PM   #40
pdurrant
The Grand Mouse 高貴的老鼠
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Oh, I like that one. Very neat. I think I'd simplify by subtracting 30, not 32 and not using the 1/100 term. The two simplifications almost cancel out for extreme temperatures (>100°C or < 100°C)and subtracting one if the answer is double figures or less fixes that.

Quick, what's 450°F in Celcius?

thinks... 450-30=420, 420/2 = 210, 210/10=21, answer = 231 (precise answer is 232.222.....)

How about -200°F
230/2 = 115/10=11, answer = -126°C (precise answer is -128.8888

68°F: 38/2= 19/10 = 1.9, answer = 21°C -1 = 20 (precise answer is 20)

20°F -10/2 = -5/10 = -0.5, answer = -5.5 -1 = -6.5 (precise answer is -6.6666)

Quote:
Originally Posted by Who are you? View Post
5/9 happens to be 0.55555, the observing person quickly sees how you can calculate that, it's ½ + ½ /10 + ½ /100

So for the 50°F example the result is
50 -32 = 18
18 / 2 = 9
9 + 0.9 + 0.09 ≈ 10°C
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