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Powers and Roots Practice Test 3

Question : 4 of 40

Marks: +1, -0

Find the square of 489 among the following:

Solution:

Concept:

To find a square, multiply the number by itself and use digit patterns to verify the answer.

Explanation:

(489)^2 = 489 \times 489

Use the identity

(500-11)^2 = 500^2 - 2(500)(11) + 11^2

= 250000 - 11000 + 121

= 239121

Also, the square of an odd number ends in an odd digit, and a 3-digit number’s square has at least 5 or 6 digits.

Only

239121

matches these conditions.

Answer:

(489)^2 = 2,39,121

The correct option is C.

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