Angels & Demons - Dan Brown
"What is it with this guy and speed? he wondered.
'Five kilometers to the lab,' the pilot said. 'I'll have you there in two minutes.'
Longdon searched in vain for a seat belt. Why not make it three and get us there alive?

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'(...) The number 503 in Roman numerals is-'
'DIII.'
Langdon glanced up. 'That was fast. Please don't tell me you're an Illuminatus.'
She laughed. 'I use Roman numerals to codify pelagic strata.'
Of course, Langdon thought. Don't we all."