To change latitude and longitude from decimal notation to minutes and seconds, follow the following algorithm:

1) Enter the decimal number into your calculator
2) Subtract the whole portion of the number.
Example: If the decimal number is 86.1235, you subtract 86
3) There are 60min/1°; so multiply the remaining decimal number by 60.
The whole portion of the result is your minutes.
4) Now, subtract off the whole portion of this last result. (Subtract off the minutes.)
5) There are 60sec/1min; so multiply the remaining decimal number by 60.
This number is the seconds.

To change latitude and longitude from minutes/seconds notation to decimal notation, do the following:

1) Enter the seconds into your calculator.
2) There is 1min/60sec; so divide by 60.
3) Add the minutes to this result.
4) There is 1°/60min; so divide by 60 again.
5) Add the degrees to this result.
The resulting number is the decimal representation.

For more info on latitude and longitude, see the Geology Club links page or, for real depth, try this.