more than versus over

[choufleur]

when should you say 'more than' and when 'over'?

for example is "we have more than 100 years experience" or "over a 100 years experience" correct?

Where I work, I always have to say "more than." It's our house style. But I don't know why.

More than is simply more elegant. Over isn't necessarily incorrect but it's infelicitous at best. Most newspapers will have "more than" as house style.

"Over a 100 years experience" is just wrong. "Over a hundred..." would be better.

It should be "more than 100 years' experience"