Hours.Decimal Hours

[Gamo]

Got question on how to convert 100 second to Minute Second.

When I use the Casio calculator that have [H/M/S] function simply press

0 [H/M/S] 0 [H/M/S] 100 [H/M/S] display shown answer 0-01'40"

So 100 second is 1 minute and 40 second

How to calculate this on like HP-11C or HP-15C ?

I try on HP-11C by first do the 100 ÷ 60 and got 1.6667 then press [FRAC]

for only the fractional part 0.6667 and press [→H.MS] display answer 0.4000

So add that 1 minute back will get 1.4000

Is this suppose to be the right way to calculate this kind of problem?

Thank You

Gamo

[ijabbott]

You don't need to press [FRAC]. Just convert the 1.6667 via [→H.MS] to 1.4000.

The H.MS conversion is being abused, so will not work if the number of seconds is not an integer.

To convert seconds to H.MS form properly, divide seconds by 3600 (or 60²) and press [→H.MS].

[Gamo]

Thanks ijabbott

Just convert the 1.6667 via [→H.MS] to 1.4000

That's all.

Gamo

[C.Ret]

(01-20-2022 09:31 AM)Gamo Wrote:  Just convert the 1.6667 via [→H.MS] to 1.4000

Hi,

This is only correct by chance ! And you may obtained an incorrect result with a different input.

The goal of the →H.MS instruction is to convert any time value into HH.MMSSs format (alternatively into angular DDD°MMSSs).

To convert 100 seconds the correct algorithm is to divide 100 by 3600 and then to shift-press the →H.MS key.
Dividing by 60 only works for integer seconds, in case of fractional seconds you will get incorrect tenth of second.


100/3600 is 0.0277778 which is converted by →H.MS into 0.01400 that indicate 0 : 1' 40.0"

[Joe Horn]

Here's one way of doing it on the HP-15C which is not the most efficient but is easily understood:

Type 0.0001 (that's one second in HP's HMS format)
→H (to convert to decimal hours)
100 × (to multiply by 100)
→HMS (converts the result to 0.0140, that is, 0 hours, 1 minute, 40 seconds)

[Gamo]

Thanks all for the answer.

Gamo