The Clever Way to Count Tanks - Numberphile

How mathematics and probability cracked the puzzle of how many tanks were being produced by Nazi Germany during World War 2.

NUMBERPHILE

Videos by Brady Haran

[dowesschule]

You didn't just pull out the first and last, but also the middle tanks 15&16!

[fatsquirrel]

Pointing out that lower numbers are more likely is such a good observation. Brady keeps highlighting his genius video after video.

[redryder]

I know it's irrelevant, but there's the old joke about letting three sheep loose in a field, but first labelling them "1" "2" and "4" so the person rounding them up spends ages looking for the 3rd.

[courtney-ray]

At 6:36 you were right on! The gap below your minimum observation WAS equal to the gap above the maximum observation and the true number of tanks!

[adsilcott]

6:33 I love the way the turrets are pointing at their actual positions in the number line :)

[GrimOrdnance]

I adore the fact that you left the initial pull in the video, because that is the truth in probabilities. I appreciate your videos!

[polyaddict]

I love how british "they have a bit of a spy" is

[funnygeeks]

1:22 "after the war, the allies can go into those tank making factories"

I like how knowing if our math was right is more important than having won the war.

[MuffinsAPlenty]

Watching James Grime explain mathematics is such a joy.

[LeonMatthews]

For several of my clients we incremented the serial number by some prime, rather than one, than in order to obfuscate the output somewhat. It also gave us some degree of parity checking on serial numbers later. Silly, really, but fun.

[mark]

This only works of the serial numbers are sequential. Knowing this, the US named the the third SEAL team "SEAL Team 6" to confuse Soviet intelligence.

[otaviodiniz]

Man, it's 11pm local time, I'm awake since 4am, my week was a rollercoaster, I'm mad about my job, I'm dealing with a woman that is getting in my nerves, my bank account is zeroed, I'm tired and pissed...
But for some reason, his enthusiasm telling this story made me happy instantaneously.

Thank you for this, God bless you and your beloved ones. Got a subscription.

[jameswkirk]

A company I worked for made computers & peripherals and used 64 bit random serial numbers. They had multiple manufacturing sites, and calculated that the odds of selecting two identical numbers was smaller than human bookkeeping and errors trying to coordinate multiple product lines.

[boodzy]

I thought I was smart with my calculation of (1+15+16+23+30)/5x2 = 34 but this guy pulls out a giant sheet of paper and introduces probabilities.

[Limrasson]

His reaction to tank 30 immediately raised suspicion and I would have said "yeah, that's 30 tanks in the bag."

[gustavakerman]

Alternative title: Local British mathematician gets blindsided by sheer stupid luck

[art]

No war thunder sponsor? Missed opportunity

[EchosTackyTiki]

In arms production it's fairly common for factories to assign serial number ranges to particular products in advance, so the serial number ranges having gaps within them is relatively normal. It's also normal for them to start production at something like 10, 000 if they expect to make in the tens of thousands of that particular item, that way they all the items are serialized, but they also maintain the same number of digits in their serial number for uniformity without using a bunch of leading zeros. Overrunning that serial range usually results in a letter prefix or suffix being added.

[jamesterwilliger]

Spies be like "tank you very much" but the mathematicians be like "tanks but no tanks"

[bittencourt]

I've just simulated 10000 of this operation for number of tanks less than 100 and number of guesses between 10 and 50, and using the maximum value as the total of tanks gives 4 on an average error, while using the maximum value + average gap leaves 2.6 as average error. That method is simply 151% more precise!! Amazing!!!