Rose Blumkin, who founded the Nebraska Furniture Mart in 1937, helped her son and grandchildren build it into the nation's largest home furnishings store and continued selling carpet there well past her 100th birthday, died on Friday in Omaha. She was 104.

Mrs. B, as she was fondly known by Midwesterners who often traveled hundreds of miles to Omaha to shop at the store, was known for her credo: ''Sell cheap, tell the truth, don't cheat nobody.'' In her last years, she moved around the cavernous store on a golf cart, sometimes startling visitors by abruptly zipping away toward customers who appeared to be waiting for attention.

Mrs. Blumkin stood just 4 feet 10 inches in her prime, but her merchandising skills and daring as she made the long journey from an impoverished childhood in Russia to success led figures like Warren E. Buffett to rank her as a business giant. At one point soon after founding her store, she sold every appliance and piece of furniture in her home to pay off a debt. When furniture manufacturers stopped selling directly to her after bigger customers in Omaha complained about her low retail prices, she traveled to Kansas City, Mo., Chicago and New York, bought from department stores and still undersold her rivals.

''Put her up against the top graduates of the top business schools or chief executives of the Fortune 500 and, assuming an even start with the same resources, she'd run rings around them,'' Mr. Buffett said in 1984 soon after Berkshire Hathaway Inc. bought majority control of the Furniture Mart from Mrs. Blumkin. Based on his experience as a customer and as an acquaintance of her children, Mr. Buffett made the acquisition on a handshake without bothering to audit her books or inventory.