Many of his installations were accented with words or numbers in neon. The numbers counted off the Fibonacci progression, the mathematical formula (named for the Italian monk and mathematician Leonardo Fibonacci who discovered it) for growth patterns found in many forms of life, including leaves, snail shells, pine cones and reptile skins. The pattern is identifiable as a sequence of numbers in which any given number is the sum of the two numbers that precede it: 1, 1, 2, 3, 5, 8, etc., ad infinitum. From 1969 Merz employed the Fibonacci sequence in performances and installations throughout his career to represent the universal principles of creation and growth: climbing up the Guggenheim Museum in New York (1971) or the spire of a Turin landmark (1984), or perched in neon on a stack of newspapers among the old masters of Naples' Capodimonte Gallery (1987). In 1972 he illustrated the Fibonacci progression with a series of photographs of a factory workers' lunchroom and a restaurant progressively crowded with diners. His 1973 show at the John Weber Gallery in New York expressed the Fibonacci in a series of low modular tables. In 1990 the sequence determined the form of a spiral assembled from sticks, iron and paper across 24 meters of a hall in Prato, near Florence. An installation of Fibonacci numbers by Merz is the landmark of the Centre for International Light Art in Unna, Germany.
By the time of his first solo museum exhibition in the United States, at the Walker Art Center, Minneapolis, in 1972, Merz had also added stacked newspapers, archetypal animals, and motorcycles to his iconography, to be joined later by the table, symbolizing a locus of the human need for fulfillment and interaction.