Calculated Industries 9130 - Time Conventions and Math Rules

12 — Time Master II
Time Conventions
When you are dealing with time, there
are actually two kinds of time values that
must be considered:
1. Points in Time: 9:22 AM, 5 PM
2. Time Periods: 37 Minutes, 45
Seconds
The time math rules are as follows:
Addition
Period + Period = Period
3 Hrs. + 22 Min. = 3 HR 22 MIN
Point + Period = Point
9 AM + 22 Min. = 9:22 AM
Point + Point = Error
Note: You cannot add two points
in time as the result would be
meaningless.
Subtraction
Period – Period = Period
3 Hrs. – 22 Min. = 2 HR 38 MIN
Point – Period = Point
9 AM – 22 Min. = 8:38 AM
Point – Point = Period
9 AM – 8:30 AM = 30 MIN
Period – Point = Error
Note: When subtracting one point in
time from another, it’s best to enter
the “later” time first, then subtract the
earlier time.