Carlos Slim Helu vs. Amancio Ortega

Every Sunday, Slim's father would give him a 5-peso allowance and required him to record his purchases in a ledger. Before going into business, Slim taught algebra at UNAM, a university in Mexico City.

Ortega first began his career manufacturing textiles through a small family company in 1963. He owns a 10% stake in Spanish telecoms firm Telxius and 5% of publicly traded natural gas grid operator Enag's.