Which of the following is the largest digit?

Question

Examoogle · Accepted Answer

The correct answer is Option B: 1. Use the divisibility rule for 9: the sum of the digits must be a multiple of 9. Since $5+2+1=8$, the next multiple of 9 is 9, so $8+k=9$, giving $k=1$.

Step-by-Step Solution & Concepts:
Shortcut Trick: Use the divisibility rule for 9: the sum of the digits must be a multiple of 9. Since $5+2+1=8$, the next multiple of 9 is 9, so $8+k=9$, giving $k=1$.

Formula Used: $$	ext{Sum of digits} = 5 + k + 2 + 1 = 8 + k$$

Given: A 4-digit number 5k21 is divisible by 9, where k is an unknown digit.

Steps: Apply divisibility rule: A number is divisible by 9 if the sum of its digits is a multiple of 9. Here, the number is $5k21$.. Find the multiple of 9: We need $8 + k$ to be a multiple of 9. Since $k$ is a single digit (0-9), the only possible value is 9.. Calculate k: Solving for $k$ in the linear equation:

Answer: B is correct because for the sum of digits $8+k$ to be divisible by 9, $k$ must equal $1$.

Exam Tip: This rule is identical to the divisibility rule for 3 (sum of digits must be divisible by 3). Always check if you are looking for divisibility by 3 or 9 in similar problems.

Correct Answer

Solve 10,000+ More Questions with AI Tutor

Discussion (0)

Correct Answer

Solve 10,000+ More Questions with AI Tutor

Related Questions

Discussion (0)