Calculated Industries Construction Master III User Manual page 45

Hip or Valley, "Jack Rafters"
— with other than 16" on-center
You're again working with a 7-in-12 Pitch and
the Run of the common rafter is 30 feet 9 inches.
You want to calculate the length of your jack
rafters at 18 inches o.c. You'll need to enter 18
inches o.c. into the [Jack] key before you find the
lengths of the jacks:
COMMENTS
Clear calculator
Enter Pitch
Enter Run of common
Enter 18" o.c. *
Recall to verify 18" o.c. [Rcl] [Jack]
Find 1st Jack
Find 2nd Jack
Find 3rd Jack
Find 4th Jack
Etc., Etc.
Repeat, until all jacks are found, or when
calculator displays "0 FT 0 IN."
* You do not need to label the 18 as "inches" — the
calculator will automatically assume an inch format.
KEYSTROKES
[On/C] [On/C]
7 [Inch] [Pitch]
30 [Feet] 9 [Inch] [Run]
18 [Jack]
Answer: 18 IN JK
[Jack]
Answer: 33 FT 10-23/64 IN
[Jack]
Answer: 32 FT 1-33/64 IN
[Jack]
Answer: 30 FT 4-43/64 IN
[Jack]
Answer: 28 FT 7-27/32 IN
User's Guide — 45