A little mathematics

A few months ago I had gotten myself a travel insurance. But for some reason it never happened: the money wasn't taken from my account. So, yesterday I went back to get the thing sorted properly. As I was there anyway I wanted to know how much my car insurance was as well. And then it started to get complicated. 

Now, there are 365 days in a year (apart from leap years, but it's not this year). And there are twelve months. Nothing complicated so far. In the Netherlands, they calculate your monthly insurance payments by seeing how much insurance they want you to pay in a year and then dividing it by twelve. Giving you twelve equal payments (365/12). Not so over here...

Here they have decided that would be too simple. In stead they divide the amount (x) by 365. Then they use that number (x/365) and multiply that by 30. As in days of one month. But, since not all months are 30 days long, they only let you pay that amount 7 times. After that they use that number (x/365) and multiply it by 31. Which you have to pay for the remaining 5 months. 

Clearing it up a bit: if x equals 365 and you divide that by the number of days in an ordinary year you get 365/365=1. You then multiply that number by 30: 30*1=30. Which you pay for seven months: 30*7=210. The other 5 months you have to pay: (31*1)*5=155. Adding 210 to that 155 you get 365. Of course in a leap year there will only be six months of 30 and then six months of 31. I presume. 

You are wrinkling your forehead now aren't you? The sums are easy enough, you all get it, but you know that there are not seven months of 30 and five months of 31 days in the year. For a start February only has 28! Plus there aren't only five months of 31 days either! There are seven (Jan/Mar/May/Jul/Aug/Oct/Dec)! What can I say: the Norwegians probably felt it was a good thing to difficultise a very simple thing and then decided it was too difficult and tried to simplify it again. 

It made my head swim a bit though...