This question asks to identify which electronic equipment uses Binary Coded Decimal (BCD) numbers. Let's explore the role of BCD in the given options.

Understanding BCD Numbers

Binary Coded Decimal (BCD) is a numeral system where each digit of a decimal number is represented by a unique sequence of bits, typically four bits. For example, the decimal number '5' is represented as 0101 in BCD, and '9' is represented as 1001. BCD is often used in digital electronic systems where a decimal display is required, as it simplifies the conversion between decimal and binary representations.

BCD Application in Equipment

BCD finds application in various digital devices:

• Pocket Calculators: These devices perform arithmetic operations and display results in decimal format. BCD is commonly used internally to handle the decimal digits, making it easier to drive the decimal display units.
• Electronic Counters: Digital counters often need to display count values in decimal. BCD logic is frequently employed in the counter circuits and their display drivers to manage and present the decimal count accurately.
• Digital Voltmeters (DVMs): DVMs measure voltage and display the reading digitally. The processing and display sections of a DVM often utilize BCD to represent the measured voltage in a user-friendly decimal format.

Since pocket calculators, electronic counters, and digital voltmeters all frequently process and display decimal information, they commonly employ BCD representation in their internal circuitry or display logic.

Conclusion on BCD Usage

Given that all the listed devices (pocket calculator, electronic counter, digital voltmeter) typically operate with decimal numbers and often utilize BCD for internal processing and display management, the most appropriate answer is that they all use BCD numbers.