: : 6. Which of the following fractions has a equivalent that is a terminating : : decimal ? : : A. 10/189 B. 15/196 C. 16/225 D. 39/128 : : Ans: D (看不懂题目) : 个位数2 or 5结尾的是terminating decimal(注意需不需要约分) : : 以上六题 恳请解答!! google到比较完整的题目..你的D选项等於以下答案选项的E选项.. 题目应该是问哪个分数换算成小数位会终止..不会进入循环小数 Which of the following fractions has a decimal equivalent that is a terminating decimal? A. 10/189 B. 15/196 C. 16/225 D. 25/144 E. 39 /128 First of all we should look for denominator characteristics. If any denominator is a prime no. except 2 or 5, then it would be a repeating decimal fraction. (主要是用分母的数值进行因式分解来判断.质数除了2和5.其他皆会造成循环小数) If the denomiantor is a multiple of 3, the result is repeating decimal fraction. (分母为3的倍数时..为循环小数) Here, A, C, D represent repeating decimal fraction. (A,C,D皆为3的倍数..所以是repeating decimal fraction) Here, we can not factorize 196(2*2*2*2*11) in 2^n*5^m fashion but 128=2^7*5^0. (因式分解B和E) So, B represents repeating decimal fraction and E terminating decimal fraction (B选项有个因子为11(非2or5)..会造成循环..所以E应该是正解.. --

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