For the ten-year period 1962–72 Fletcher pursued summer employment as a mathematical applications computer programmer in industry, business, and government at IBM Mohansic Laboratory (Yorktown Heights, NY), Western Electric (Hopewell, NJ), the Lawrence Livermore Laboratory (Livermore, CA), and the US Departments of Commerce (Washington, DC), Agriculture (St. Paul, Minn), and Energy (Livermore, CA).
During the ten-year period from 1962 to 1972, Fletcher had summer employment as a mathematical applications computer programmer in various sectors, including industry, business, and government, at locations such as IBM Mohansic Laboratory, Western Electric, the Lawrence Livermore Laboratory, and US departments of Commerce, Agriculture, and Energy.