HOW ABOUT ONE THOUSAND DOLLARS?!!!

That's the kind of math Chad Ochocinco is all about -- and he proved it Monday, by dropping a killer tip at one of his favorite restaurants.

The ex-NFL wideout popped by Havana's restaurant near Ft. Lauderdale -- which recently reopened amid the COVID-19 pandemic.

Not only did Chad order up some delicious grub, but man -- he blessed the good people with a some serious tippage!

"Congrats on reopening, sorry about the pandemic, hope this helps," Ochocinco wrote on the bill ... "I love you!"

The restaurant staff felt the love and publicly shouted out the former Cincinnati Bengals star on social media.

"We would like to thank Chad 'Ocho Cinco' Johnson for his continued patronage."

"We greatly appreciate your generosity to our employees now during these most difficult times. Many blessings to you and your family. Thank you again!"

We know what you're thinking -- how rich is that dude? Johnson reportedly made close to $50 mil during his 11 year NFL career ... but he's famously thrifty with his cash.

... but hey, it's good to make an exception once in a while!

Props to Chad!