@Luke M
Hi, smiling!
First, let us see the table with my updated columns as yours so as to compare them:
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[pre]
Code:
Birthday Age Luke M Back date Luke M Age SirJB7 Back date SirJB7 Age differences Back date differences
01-abr-80 33 29-sep-12 32 01-oct-12 1 -2
02-mar-82 31 30-ago-12 30 02-sep-12 1 -3
31-ene-84 29 31-jul-12 28 31-jul-12 1 0
31-dic-85 28 30-jun-13 27 30-jun-13 1 0
01-dic-87 26 31-may-13 25 01-jun-13 1 -1
31-oct-89 24 30-abr-13 23 30-abr-13 1 0
01-oct-91 22 31-mar-13 21 01-abr-13 1 -1
31-ago-93 20 28-feb-13 19 28-feb-13 1 0
01-ago-95 18 29-ene-13 17 01-feb-13 1 -3
01-jul-97 16 29-dic-12 15 01-ene-13 1 -3
01-jun-99 14 29-nov-12 13 01-dic-12 1 -2
01-may-01 12 29-oct-12 11 01-nov-12 1 -3
01-abr-03 10 29-sep-12 9 01-oct-12 1 -2
01-mar-05 8 29-ago-12 7 01-sep-12 1 -3
30-ene-07 6 30-jul-12 5 30-jul-12 1 0
30-dic-08 5 29-jun-13 4 30-jun-13 1 -1
30-nov-10 3 30-may-13 2 30-may-13 1 0
30-oct-12 1 29-abr-13 0 30-abr-13 1 -1
[/pre]
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From which I can conclude:
a) You use a strange and inexact way to establish a 6 month period (182.5 or 183 days), I rather prefer to use a straight 6 months value: that explains the slight differences in last column ranging from 0 to 3 in absolute values.
b) You're clearly older than me as I always suspected, but until now I hadn't any proof: regarding 6th column (F) you're 1 year older than me, who still remain always the same (Led Zeppelin dixit), i.e., just a little kid. Unless your maths using imperial date system works different, who knows!, or unless you rounded the years... take the 1st 2 cases: 33 vs 32, 31 vs 30, and I stick with my version, integer years.
c) Regarding your immediate previous post, I don't arrive to those dates, please check my 5th column (E). Are you still using Julian calendar? Move on!
My formulas:
D: =AÑO(C2-A2)-1900 -----> in english: =YEAR(C2-A2)-1900 ... i.e, the inner part of my original formula.
E: =FECHA.MES(A2;(AÑO(C2-A2)-1900)*12+6) -----> in english: =EDATE(A2,(YEAR(C2-A2)-1900)*12+6) ... my original formula, column shifted.
So either I'm missing to see a pair of elephants within a toilette (and I should go again to the oculist, but I think he doesn't want to see me, if unless he were a she...) or you're actually fried as you said:
http://chandoo.org/forums/topic/formula-challenge-006-whats-the-number-you-can-confirm-is-a-prime-or-not#post-124343
Regards!