# Help with calculating time

• Aug 4th 2009, 08:54 AM
shamunda
Help with calculating time
Hello

I have an issue that i'm not familiar with and again equally not knowledgable to do...so i'm looking for the answer.

the minimal increment a time to calculate on a spreadsheet that i'm working on is .25 minutes. If a user work time is 7.16 then his time within the spreadsheet is represented as 7.25.

My question what is the calculation to make sure any number below .25 is rounded up to .25?

Any help appreciated.

-Shamunda
• Aug 4th 2009, 10:12 AM
Wilmer
Quote:

Originally Posted by shamunda
My question what is the calculation to make sure any number below .25 is rounded up to .25?

Are you sure that's all...what if it was 7.52:
wouldn't you want that rounded to 7.75?

Plus do you always want the next UP?
Wouldn't you want 7.52 to be 7.50...the one closest?
• Aug 4th 2009, 10:22 AM
AlephZero
If I understand your question correctly, you just want to know how to round up to the quarter-minute. I assume that you're writing a computer program? I can tell you how to represent the problem mathematically in terms of functions, and then perhaps someone else can provide some efficient psuedocode.

Let $\displaystyle T$ represent the time worked in minutes. We want to round $\displaystyle T$ up to the nearest quarter-minute. Thus we're only concerned with the fractional portion of $\displaystyle T,$ let's call it $\displaystyle (T)$, and let's call the integer portion $\displaystyle [T].$ Let $\displaystyle T_r$ be the rounded time. Then

$\displaystyle T_r=\begin{cases} [T]\quad\text{if } (T)=0 \\ [T] + 0.25 \quad\text{if } 0<(T)\leq 0.25 \\ [T] +0.5\quad\text{if } 0.25<(T)\leq 0.5 \\ [T] + 0.75\quad\text{if } 0.5<(T)\leq 0.75 \\ [T] + 1\quad\text{if } 0.75<(T)<1 \end{cases}$
• Aug 4th 2009, 11:36 AM
HallsofIvy
I imagine shamunda wants a formula that can be used in the spreadsheet. Of course, spreadsheets vary but Microsoft Excel has built in function "Floor" such that "Floor(A3, 0.25)" will reduce the number in Cell A3 to the closest multiple of .25 below the number in A3.
• Aug 4th 2009, 02:27 PM
shamunda
I would like to thank all of you!!
Quote:

Originally Posted by AlephZero
If I understand your question correctly, you just want to know how to round up to the quarter-minute. I am assume that you're writing a computer program? I can tell you how to represent the problem mathematically in terms of functions, and then perhaps someone else can provide some efficient psuedocode.

Let $\displaystyle T$ represent the time worked in minutes. We want to round $\displaystyle T$ up to the nearest quarter-minute. Thus we're only concerned with the fractional portion of $\displaystyle T,$ let's call it $\displaystyle (T)$, and let's call the integer portion $\displaystyle [T].$ Let $\displaystyle T_r$ be the rounded time. Then

$\displaystyle T_r=\begin{cases} [T]\quad\text{if } (T)=0 \\ [T] + 0.25 \quad\text{if } 0<(T)\leq 0.25 \\ [T] +0.5\quad\text{if } 0.25<(T)\leq 0.5 \\ [T] + 0.75\quad\text{if } 0.5<(T)\leq 0.75 \\ [T] + 1\quad\text{if } 0.75<(T)<1 \end{cases}$

Yes That's exactly what i'm looking for!! I apologize for my late response but yes that's exactly what i'm looking for. I can write out the code for it, but i'm afraid my math skills are greatly inefficient (Thinking)

Sham
• Aug 6th 2009, 01:26 PM
shamunda