It means he fits more per suitcase when he leaves office. 2.5 x more then with $100 notes.
See, I am starting to get his thinking here.
$1 million in 100s fits into an airline carry on case. That, 40 liters volume. A 747-8 Jumbo, like the one Qatar "gifted", has a 120 thousand liter hold, so that's 3000 40 liter cases.
So at 100 buck notes thats 3000 million. 7500 million in 250 buck notes