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Dan Rubin's SuperfluousBanter

Suffering from chronic idiocy since 1977

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Interview by Justin Goodlett (and win $20!)

Interview with Didier HilhorstI’m
excited to announce my
first ever inter­view by Justin Goodlett of Skin­nyJ.
Pre­vi­ous inter­vie­wees include Jon Hicks and Andy Arikawa — need­less to
say I find myself in good com­pany. I answer ques­tions about design, aes­thet­ics,
usabil­ity, Jakob Nielsen, inspi­ra­tion and how I became to be a designer. Enjoy!

But wait…

There’s more! In the inter­view
I chal­lenge read­ers to cal­cu­late my age using a math­e­mat­i­cal for­mula. The first
reader to post a cor­rect answer along with a ratio­nale of the cal­cu­la­tion in
the com­ments will win a $20 gift cer­tifi­cate
from amazon.com. That’s as many dol­lars as nec­es­sary to buy a copy of
the new required read­ing by the folks at 37signals
enti­tled Defen­sive Design
— heck, you’ll even have enough left to grab a beer at your local
pub.

Update: There are some mucho smart and espe­cially light­en­ing fast peo­ple on the web. Damn. You’ve guessed it: the $20 gift cer­tifi­cate has been won, already. Con­grat­u­la­tions to both Shaun and David for the answers. They both get $20. So, what did you think of the inter­view? Discuss!

 

This item was posted by dhilhorst on Tuesday, March 23rd, 2004.

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12 comments on “Interview by Justin Goodlett (and win $20!)”

  1. Posted by Bob on Tuesday, March 23rd, 2004.

    You’re 24.

  2. Posted by Bob on Tuesday, March 23rd, 2004.

    Oops, for­got the rationale:

    Because Google Cal­cu­la­tor said so. ;-)

  3. Posted by Bob on Tuesday, March 23rd, 2004.

    Sheesh… one day I’ll learn to click on hyper­links in order to post in the cor­rect com­ments. I’m such a dum­b­ass. Feel free to delete these com­ments. Or leave them up for the amuse­ment of oth­ers. It’s your call. :-/

  4. Posted by David on Tuesday, March 23rd, 2004.

    54^7 = 1338925209984

    1338925209984 mod 65 = 24

  5. Posted by David on Tuesday, March 23rd, 2004.

    if that’s not enough detail:

    the ^ means the first raised to the power of second

    mod means the remain­der when the first is divided by the second

  6. Posted by Didier Hilhorst on Tuesday, March 23rd, 2004.

    Very well done. Cal­cu­la­tors make life easy. Now the hard part…

    Although you were all able to per­form the cal­cu­la­tion you didn’t pro­vide me with a sat­is­fac­tory ratio­nale. I was expect­ing the cal­cu­la­tion itself to be solved rather quickly.

    How­ever I need an expla­na­tion of how mod­ulo (mod) works and not just a descrip­tion of the for­mula. Include a sim­ple exam­ple along with a sum­mary in words of how it is actu­ally being cal­cu­lated and the $20 is yours! But don’t for­get to post it on SkinnyJ.

  7. Posted by waylman on Tuesday, March 23rd, 2004.

    Ok, that was a cool con­test. Funny thing is I majored in math and even com­pleted 2 semes­ters of cal­cu­lous with the local com­mu­nity col­lege in my last year of high­school, yet I don’t ever remem­ber see­ing ‘mod­ulo’. Not that I didn’t, I just don’t remem­ber. Of course it has been a few years since I used any of that stuff.

    Any­way, just won­der­ing if there is a easy equa­tion to find how any­ones age would be resp­re­sented like that. I’m look­ing for a way to give my age (or any­ones) and have it spit out the equa­tion rep­re­sent­ing that age.

  8. Posted by James on Tuesday, March 23rd, 2004.

    [I thought I’d post this here too.]

    For a non-calculator solu­tion (if anyone’s interested),

    If a (mod x) = b (mod x)

    and c (mod x) = d (mod x),

    then a*c (mod x) = b*d (mod x).

    Note also that neg­a­tives are per­mis­si­ble in mod­ulo arith­metic, and any num­bers with the same remain­der in the cor­re­spond­ing base are equal (con­gru­ent). In other words,

    54 (mod 65) = –11 (mod 65).

    Con­tin­u­ing (all in mod 65),

    54^2 = (-11)^2 = 121 = –9

    54^4 = 54^2 * 54^2 = –9 * –9 = 81 = 16

    54^6 = 54^4 * 54^2 = 16 * –9 = –144 = –14

    54^7 = –14*-11 = 154 = 24

    There­fore, DH is 24.

  9. Posted by Didier Hilhorst on Tuesday, March 23rd, 2004.

    Some might think that stat­ing my age with a math­e­mat­i­cal for­mula is rather eso­teric. But I thought it would be a nice chal­lenge (it turned out to be to easy a chal­lenge). So why mod­ulo you ask? What’s so great about it?

    I find num­bers fas­ci­nat­ing. Prime num­bers, Fibonacci sequence, Cae­sar cipher (sim­ple shift cipher) and things alike. Cryp­tog­ra­phy plays an impor­tant role in tech­nol­ogy secu­rity (online, offline and basi­cally every­where). Mod­ulo aritch­metic is used in pub­lic key cryp­tog­ra­phy: RSA. Of course there’s much more to cryp­tog­ra­phy than just mod­ulo arithmetic.

    I’d like to thank James for his non-calculator solu­tion since it nicely shows how it works. I always use a sim­ple exam­ple to explain how it works. Take 3^2(mod)2 for example.

    3^2(mod)2 = 9(mod)2

    2 * 4 = 8 (2 fits 4 times in 9)

    9 — 8 = 1 (which is the remainder)

    there­fore: 3^2(mod)2 = 1

    I think this should be enough math­e­mat­ics for a whole year. Back to impor­tant things! Back to design and interfaces!

  10. Posted by Jeff Minard on Tuesday, March 23rd, 2004.

    For fur­ture ref­er­ence, the eas­i­est way to mark up Mod­u­lus is with a % sign. ie:

    2%1 == 1

    or

    (3^2)%2 == 1

    In addi­tion, mod­u­lus is really easy to fig­ure out with­out a cal­cu­la­tor. Sim­ply sub­tract the mod­u­lus num­ber until the reult is less than the mod­u­lus oper­a­tor. This method seems a lit­tle eas­ier than the one posted a few com­ments above by James. A few examples:

    9%2 = 1

    -

    9–2 = 7 (7 < 2) { false }

    7–2 = 5 (5 < 2) { false }

    5–2 = 3 (3 < 2) { false }

    3–2 = 1 (1 < 2) { true }

    5%3 = 2

    –

    5–3 = 2 (2 < 3) { true }

    7%2 = 1

    –

    7–2 = 5

    5–2 = 3

    3–2 = 1

    19%4 = 3

    –

    19–4 = 15

    15–4 = 11

    11–4 = 7

     7–4 = 3

    For a neg­a­tive num­ber, I imag­ine you can just drop the neg­a­tive oper­a­tor (work on it’s absolute value).

  11. Posted by Sunny on Tuesday, March 23rd, 2004.

    Didier — I am sure the fig­ures are per­fectly rounded!

  12. Posted by Goughe on Tuesday, July 27th, 2004.

    ooud­faqmhc bjaf.