Minutes to hours in decimal + round in C#

Question

I'm trying to convert minutes to hours in decimal and round to the nearest fifteen minutes (rounded up).

Basically:

15 minutes = 0.25 hour

25 minutes = 0.5 hour

30 minutes = 0.5 hour

50 minutes = 1 hour

60 minutes = 1 hour

I haven't found anything relevant here on stackoverflow but another website tells me to:

var hours =  Math.Round((minutes * 100 ) / 60.0);

Which doesn't come near to the result.

I know I can't use Math.Round() (because it casts it to an int?). Same for TimeSpan (because it gives .TotalHours in a double).

What can a good approach be starting with dividing it by 60?

Actually 50 minutes would be 0.75 hour because it is closer to 45 than to 60. — stelioslogothetis, Jul 20 '17 at 14:42
Math.Floor and Math.Ceiling will return ints. Since you want a double, I think your best bet is divide by 60.0 then use some if statements — Matt L., Jul 20 '17 at 14:45
[Thats not true](https://msdn.microsoft.com/en-us/library/zx4t0t48(v=vs.110).aspx) @MattL. — Liam, Jul 20 '17 at 14:46
You might need to modify it slightly to `Math.Ceiling(minutes/15D)/4` — Liam, Jul 20 '17 at 14:47
You could start by (Minutes*100/60) and then divide the result with 0.25 If the result is a total number you are done, else round up — royalTS, Jul 20 '17 at 14:50

score 8 · Accepted Answer · edited Oct 11 '17 at 10:14

8

Lets think that you have minutes and want to convert them to hours (0.25, 0.5, 0.75, 1)

First we get what quarter it is: Math.Ceiling(minutes / 15.0)

Math.Ceiling returns you 4 if you have 3.01

And then just divide it by 4 to have quarters

var hours = Math.Ceiling(minutes / 15.0)/4.0;

edited Oct 11 '17 at 10:14

Vadim Kotov

answered Jul 20 '17 at 14:49

@KahnKah can't you just cast the value to a `(double)` – Jamadan Jul 20 '17 at 14:52
@KahnKah edit it like this `var hours = Math.Ceiling(minutes / 15.0)/4.0;` Or cast values to double – Markiian Benovskyi Jul 20 '17 at 14:52
I can't parse it to a double @DarthJam – Kahn Kah Jul 20 '17 at 14:53
Thank you very much Mark – Kahn Kah Jul 20 '17 at 14:57
1

you can also use `15d` for `double` or `15m` for `decimal` https://stackoverflow.com/a/166762/89586 – Matthew Whited Jul 20 '17 at 15:01

Yves Daoust · Answer 2 · 2017-07-20T14:56:29.577

3

Use one of

depending on the exact rounding you want (nearest, down or up).

minutes / 15 tells you a number of quarters, which you round, then 0.25 converts to hours.

edited Jul 20 '17 at 14:56

answered Jul 20 '17 at 14:51

Yves Daoust

2 Answers2