算数-分数和小数

分数和小数

flyfish 2015-11-3

分数（fraction）=分子（numerator）/分母（denominator）
小数（decimal）

基数词表示分子，序数词表示分母
如果分子大于1，分母要用复数形式
1/2: a（one）half。
1/4: a（one）fourth
3/4: three fourths

一
Last week the Star Bakery made 3 kinds of cakes. One half of the cakes were made with 4 eggs each，two thirds of the rest of the cakes were made with 3 eggs each，and the remaining 54 cakes were made with 2 eggs each. What was the total number of eggs used to make all of these cakes？

余下的54块蛋糕占 剩下一半的1/3即1/2×1/3=1/6，因此蛋糕总数为54÷1/6=324，故用四个蛋的蛋糕有324×1/2=162，用3个蛋的蛋糕有324-162-54=108。因此总共用去鸡蛋162×4+108×3+54×2=1080。

二
When 1.783 is rounded to the nearest whole number，the result is how much greater than when 1.783 is rounded to the nearest tenth？

be rounded to是四舍五入的意思。本题是将1.783分别四舍五入到个位及十分位，然后计算差值2-1.8=0.2。
whole number=integer
三
If P，R，and T are digits in the positive three-digit integer PRT，what is the decimal equivalent of PRT×（10^-2）？

n-digit表示n位数。一个数乘以10n（n为正整数/负整数），小数点往右/往左移n位；将PRT看成PRT.00，故小数点往左移2位，得到P.RT

四
If 5.16 is rounded to the nearest tenth and the result is doubled，what is the final result？

5.16四舍五入到十分位得到5.2，翻倍后等于10.4