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Quantitative - Mathematics - Data Sufficiency:

Data Sufficiency

MCQ - 20-3996

Question:

What is the last digit of the positive integer n?

(1) The last digit of n equals the last digit of n2.

(2) n is an even number.

  1. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
  2. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
  3. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
  4. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
  5. Statements (1) and (2) TOGETHER are NOT sufficient.

Correct Answer: E

Explanation:

The last digit of a positive integer is the same as the last digit of n2 only when the last digit is 0, 1, 5, or 6. For example, The last digit of 10 is 0 and the last digit of 102 (= 100) is also 0. The last digit of 11 is 1 and the last digit of 112 (= 121) is also 1. The last digit of 15 is 5, and the last digit of 152 (= 225) is also 5. The last digit of 16 is 6, and the last digit of 162 (= 256) is also 6. Since we have multiple cases with Statement (1) alone, it is not sufficient.

Now, the last digit of an even number is 0, 2, 4, 6, or 8. Hence, Statement (2) alone is not sufficient.

The common solutions from the two statements are 0 and 6 (which means n ends with either 0 or 6). Since we do not have a single solution, the statements together are not sufficient. The answer is (E).

Record Performance

34 MCQ for effective preparation of the test of Data Sufficiency of Data Sufficiency section.

Read the MCQ statement: What is the last digit of the positive integer n? (1) The last digit of n equals the last digit of n2. (2) n is an even number., keenly and apply the method you have learn through the video lessons for Data Sufficiency to give the answer. Record your answer and check its correct answer and video explanation for MCQ No. 20-3996.

How to Answer

Solve the question for MCQ No. and decide which option (A through D/E) is the best choice to answer the MCQ, then click/tap the blue button to view the correct answer and it explanation.

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