For the record, TheBlackEmplelon did it incorrectly.
First, chance of 6 critical hits
The chance of a critical hit is 1/16. However, instead of multiplying the denominator by 6 which is apparently what TheBlackEmpoleon did, you need to take it to the power 6, as per probability rules.
So the chance of getting 6 critical hits in a row is (1/16)^6 = 1/16777216.
Add in the chance of a paralysis by Thunderbolt which is a 10% or 1/10 chance. To find the total chance, multiply the two figures together.
= 1/167772160 chance.
That's roughly 5.96 x 10^(-9) in Scientific notation, or around 0.000000596% chance.
TL:DR alot luckier than the other calculation made it out to be.