

InterviewSolution
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Without actual division, show that each of the following rational numbers is a terminating decimal. Express each in decimal form.(i) \(\frac{23}{2^3\times5^2}\)(ii) \(\frac{24}{125}\)(iii) \(\frac{171}{800}\)(iv) \(\frac{15}{1600}\)(v) \(\frac{17}{320}\)(vi) \(\frac{19}{3125}\) |
Answer» (i) \(\frac{23}{2^3\times5^2}\) = \(\frac{23\times5}{2^3\times5^3}\) = \(\frac{115}{1000}\) = 0.115 We know either 2 or 5 is not a factor of 23, so it is in its simplest form Moreover, it is in the form of (2m × 5n). Hence, the given rational is terminating (ii) \(\frac{24}{125}\) = \(\frac{24}{5^3}\) = \(\frac{24\times2^3}{5^3\times2^3}\) = \(\frac{192}{1000}\) = 0.192 We know 5 is not a factor of 23, so it is in its simplest form. Moreover, it is in the form of (2m × 5n ). Hence, the given rational is terminating. (iii) \(\frac{171}{800}\) = \(\frac{171}{2^5\times5^2}\) = \(\frac{171\times5^3}{2^5\times5^5}\) = \(\frac{21375}{100000}\) = 0.21375 We know either 2 or 5 is not a factor of 171, so it is in its simplest form. Moreover, it is in the form of (2m × 5n ). Hence, the given rational is terminating. (iv) \(\frac{15}{1600}\) = \(\frac{15}{2^6\times5^2}\) = \(\frac{15\times5^4}{2^6\times5^6}\) = \(\frac{9375}{1000000}\) = 0.009375 We know either 2 or 5 is not a factor of 15, so it is in its simplest form. Moreover, it is in the form of (2m × 5n). Hence, the given rational is terminating. (v) \(\frac{17}{320}\) = \(\frac{17}{2^6\times5}\) = \(\frac{17\times5^5}{2^6\times5^6}\) = \(\frac{53125}{1000000}\) = 0.053125 We know either 2 or 5 is not a factor of 17, so it is in its simplest form. Moreover, it is in the form of (2m × 5n). Hence, the given rational is terminating (vi) \(\frac{19}{3125}\) = \(\frac{19}{5^5}\) = \(\frac{19\times2^5}{5^5\times2^5}\) = \(\frac{608}{100000}\) = 0.00608 We know either 2 or 5 is not a factor of 19, so it is in its simplest form. Moreover, it is in the form of (2m × 5n). Hence, the given rational is terminating. |
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