BCD Arithmetic MCQs

Practice BCD Arithmetic MCQs with four options, answers and explanations for focused Electronics & Telecommunication Engineering revision.

Question 1

Digital ElectronicsBCD Arithmetic

In 8421 BCD addition, if a 4-bit digit sum is greater than 1001₂ (decimal 9), which binary correction is added to obtain a valid BCD result?

A0011
B0110
C1001
D1010

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Correct Answer: B. 0110

Explanation: A BCD digit is valid only from 0000 through 1001. When the binary digit sum exceeds 9, adding 0110₂ corrects the result and generates the appropriate decimal carry.

Reference: Standard digital electronics: BCD addition

Question 2

Digital ElectronicsBCD Arithmetic

Two BCD digits 0101 and 0111, representing decimal 5 and 7, are added. After BCD correction, the two-digit BCD result is?

A0001 0010
B0000 1100
C0010 0001
D0001 0110

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Correct Answer: A. 0001 0010

Explanation: 5+7=12. The initial binary sum 1100 is invalid BCD, so adding 0110 gives 1 0010. Thus the BCD result is 0001 0010, representing decimal 12.

Reference: Standard digital electronics: BCD correction