COST PRICE (1K ZX81)
By Ian McAipine, Portadown, County Armagh
From Your Computer, January 1982, Page 70

I am 14 years old, and my father and mother have a do-it-yourself and crafts
shop which sells many small items. After buying any stock, they have to
estimate their mark-up and VAT and, finally, the selling pripe of each one.

My father had set his heart on proving that a, calculator is faster than my
Sinclair ZX-81, so I set out to prove him wrong. After buzzing around the
keyboard for a few hours, I produced Cost Price.

The program first asks you to input the cost price. If it was 50p, then you
would input 0.50, or if the cost price was 6.72 you would input 6.72. Then
you are asked to input your required mark-up. You would input 1 for 50
percent, 2 for 60 percent, 3 for 75 percent, or 4 for 100 percent.

These percentages can be easily changed to suit your own requirements.
Finally, you are asked to input the quantity. The computer then prints out
the original cost price, on the left-hand side of the screen, and in the
middle it prints the price at which you should sell each one, including your
mark-up, and VAT.

When you input the cost price, you do not need to input the VAT, as the
computer calculates the VAT for you, and includes it on to the recommended
selling price. After about seven seconds, the computer returns to ask you to
input the cost price again.

When I showed this program to my father, he threw his calculator in the bin.
This program will run on an unexpanded ZX-81. The delay, before returning to
the original question again, can be shortened or lengthened, by adjusting
the Pause on line 160.
