Probably a minimum of two per column - "cutter" AND "kicker" - you have to both cut the columns AND get the ends misaligned otherwise it will "hang up".
And if it was a military scenario I would advocate two cutters and one kicker. In a military scenario you are probably getting the hell out of there because the other side is too tough - so you make sure - go for overkill - and get the **** out of there.
...and isn't "make sure by overkill" appropriate for 9/11 WTC? I mean anyone - terrorist or inside jobber - who made the dubious strategic choice to use CD would want to be sure that it worked.
AND left ZERO evidence behind.
AND ... well no point pursuing common sense and rational reasoning - we are discussing with an obsessed truther.
AND dislodge one side to ensure misalignment.
Me thirty years back but not now - I'm way out of practice and don't have the books of tables which make it easy for simple soldiers.
Yes - and bigger charges mean bigger bangs - unless you are a truther with access to bangless cutting charges.
The rest of us have this funny idea that the action of explosives which cuts steel also makes a hell of a lot of noise. And once you have heard it you wont mistake it. (I've long recommended that some of us take a bunch of truthers to an army demolition range and let them hear cutting charges - and of the scale needed for WTC column cutting. Could even be a viable strategy for US authorities to stop much of the call for "New Investigation'

) (Yeah - I know - they are not influenced by reality.)
But all of that is rational people thinking.....
And "truther thinking" is an oxymoron.