Question

Between which two consecutive integers does square root 147 lieA. 146 and 148B. 10 and 11C. 11 and 12D. 12 and 13

Answer 1

12² = 144
13² = 169

147 lies between 144 and 169, so √147 lies between
  D. 12 and 13

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It can be helpful to memorize the squares of positive integers up to 20 or 25.