“Columbus wasn’t good at math. He was Italian.......................”
He was actually one of the best “Dead Reckoning” sailors/navigators of all time. A different kind of ‘math’. That’s where you average off of potentially faulty sailing information to figure where you “probably” are (It didn’t help that the North Star starts to shift its position in the sky the further West you go, and Longitude calculations didn’t exist yet). He also probably understood it was still quite far but with favorable wind patterns (once discovered) long distances could be overcome in ships (BTW He wanted the wealth of china trade to fund a new Crusade in the Holy Land).
Consider that he led 3 MORE official expeditions once he found the New World for the Europeans (the second he led had a dozen or more ships and 1500 men) (Thats a different kind of Math too....)
Because he was an Italian (an outsider) various Spaniards used court politics against him and he was swindled out of his full reward (it was ‘one tenth of all the wealth’ his discovery generated) and had to settle with gaining a Dukedom for his descendants -— one of which still has his other Title of ‘Admiral of The Ocean Seas’, which was part of the original agreement with the Spanish Monarchs
Given the close proximity of South America to Africa, it is a wonder that sailors, especially Portuguese ones, did not sail west in search of the east Indies.....................
“It didn’t help that the North Star starts to shift its position in the sky the further West you go, and Longitude calculations didn’t exist yet”
Hipparchus discovered the precession of the equinoxes and had accurately calculated both latitude and longitude as a grid on our spherical globe in around 130 BC. The problem for a long time after this discovery was the absence of an accurate universal time keeping system to measure longitude. :)