Lauretta J. Fox
Program
3

introduces interaction between the programmer and the computer. The results will be printed in a sentence.

10 REM FIND THE AREA OF A SQUARE
20 PRINT “HOW LONG IS THE SIDE OF THE SQUARE?”
30 INPUT S
40 IF S = 0 THEN 70
45 LET A = S 2
50 PRINT “THE SIDE OF THE SQUARE IS” S
60 PRINT “THE AREA OF THE SQUARE IS” A
65 GO TO 30
70 END
Result
:

How long is the side of the square?


? (The computer waits for the value to be typed) 49


The side of the square is 49.


The area of the square is 2401.


? (Here the computer waits for the next value.) 32


The side of the square is 32.


The area of the square is 1024.


? (This process repeats until the value O is given for a side, then the program stops.)

Explanation of Program 3
:
Line 20

asks the programmer to provide the data necessary to solve the problem.

Line 30

causes the computer to stop and wait for the programmer to type in the data.

Line 40

tells the computer that the programmer is finished when O is given as the length of a side.

Line 45

provides the formula to find the area of a square. The arrow pointing upward is used to signify that S is being raised to a power. The numeral 2 is the desired power.

Lines 50

result in a printout of the words inside the

60

quotation marks as well as the values of the variables S and A

Line 65

reroutes the computer back to line 30 for the next value of S. The program continues from line 30 to line 65 over and over until the value O is typed in to stop the program.

Program
4

provides a method for finding the areas of many squares. It introduces the concept of incrementing a number.

____
10 REM FIND THE AREAS OF ALL SQUARES WHOSE SIDES
____
11 REM ARE MULTIPLES OF THREE FROM 9 TO 81
____
19 LET S = 9
____
30 LET A = S 2
____
32 PRINT “S= “ S, “A= “A
____
40 LET S= S + 3
____
41 IF S > 81 THEN 60
____
45 GO T0 30
____
60 END
Result:

S = 9

A = 81


S = 12

A = 144


S 15

A 225


S 18

A 324


. . . . . .

. . . . . .


S 75

A 5625


S 78

A 6084


S 81

A 6561

Explanation of Program
4
Line 40

S=S+3 is not an equation. It means to replace S 3 with the number whose value is 3 more than the previous value of S.

Line 41

tells the computer to stop the program when the value of S becomes greater than 81.

Line 45

reroutes the computer back to repeat lines 30, 32 and 40 until the value of S is greater than 81.
