Ready reckoner

Or: using multiples of 71 for fun and profit.

Why 71? Well, you know how a standard US 12-oz bottle is 355 mls, which is 5×71, whereas an imperial pint is 568 mls or 8×71? Well, you do now. And you know how 14 71s is 994, meaning that an imperial pint is near as dammit 8/14s or 4/7s of a litre? Well, thank me later.

You can probably see where I’m going with this.

Third Half 330 ml 12 oz US 2/3 pint
500 ml Pint
Third  = 2/3 4/7 8/15 1/2 8/21 1/3
Half 3/2 = 6/7 4/5 3/4  4/7 1/2
330 ml 7/4 7/6  = 14/15 7/8 2/3 7/12
12 oz US 15/8 5/4 15/14 = 15/16 5/7 5/8
2/3 pint 2/1 4/3 8/7 16/15 = 16/21 2/3
500 ml 21/8 4/7 3/2 7/5 21/16  = 7/8
Pint 3/1 2/1 12/7  8/5 3/2 8/7 =

To use, pick one row – or column – and memorise it; you can derive all the rest from it. Either that or print it out.

(As for why you’d want to use it, haven’t you ever wondered how to compare a pint at 6%, a 500 ml bottle at 6.8% and a US 12 oz-er at 9.6%? Now you know: they’re all exactly as strong as each other.)

UPDATE Removed the ‘US Pint’ entries and added ‘2/3’, that being a measure people reading this are actually likely to see.

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One Comment

  1. Posted 13 July, 2017 at 4:01 pm | Permalink | Reply

    Reminds me of how I hated maths at school. Fucked if I understand how to use it. Well I sort of do as I have an O Level Arithmetic from 1972, but I’ll have to cut out, keep and use a calculator. Clever though.

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