Question 15
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The table gives the last digit of a square for each last digit of the number.
| Number ends in | 0 | 1 or 9 | 2 or 8 | 3 or 7 | 4 or 6 | 5 |
|---|---|---|---|---|---|---|
| Square ends in | 0 | 1 | 4 | 9 | 6 | 5 |
Which one of these numbers can be a perfect square?
- A 8,463
- B 9,127
- C 6,858
- D 7,744 Correct
Correct Answer: Option D
Squares end only in 0, 1, 4, 5, 6 or 9
8,463 ends in 3, 9,127 in 7, 6,858 in 8 – all impossible
7,744 = 88² ✓
Trap: ending in 8 is ruled out by the table.
Answer: 7,744
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