Possible Clues:

• ATM button array
• Important flat part of a calculator
• Array of calculator buttons
• Small unit with push buttons
• A number entered here — vital to move quietly
• Penny and Bill tracking legend on an electronic device
• One used when entering Florida island apartment?
• It's important to public - address department on the phone
• Data input device for computers etc
• Perhaps remote flat -- what may be used to gain access to it, initially?