In 1977, at Southern Methodist University, she was asked to give the 23rd root of a 201-digit number; she answered in 50 seconds.[1][4] Her answer—546,372,891—was confirmed by calculations done at the U.S. Bureau of Standards by the UNIVAC 1101 computer, for which a special program had to be written to perform such a large calculation.[11]
On June 18, 1980, she demonstrated the multiplication of two 13-digit numbers—7,686,369,774,870 × 2,465,099,745,779—picked at random by the Computer Department of Imperial College, London. She correctly answered 18,947,668,177,995,426,462,773,730 in 28 seconds.[2][3] This event is mentioned in the 1982 Guinness Book of Records.[2][3] Writer Steven Smith states that the result is "so far superior to anything previously reported that it can only be described as unbelievable".[12]