就是計算所有數字的數量，而這些數字不能含有"5"這個數字

Yes, it's elegant. But at the same time, it needs to iterate all the range from zero to n. I think this way wastes a lot of time when n is a big number.

題目意思：現在有100公斤的馬鈴薯，其中水分佔了百分之99，放入低溫烤箱之後，流失了一些水分，最後水分佔全部的百分之98，請計算現在總重量是多少

Now John has potatoes and the weight of potatoes is 100 kilograms.
He thinks that the water is too much because the water accounts for up to 99 percent of the total weight, then he put potatoes in an oven.
After potatoes lose some water. The water accounts for up to 98 percent of the total weight

Please help John to calculate the total weight.

This code use 4245.654ms to pass. At the same time, i try the way of "i%10" and use 691.3118ms to pass the job.
Thanks for your reply let me know what design is well.