Single Function Machine
Numbers are entered into a function machine
1, 2, 3, 4 ….
What is happening to the numbers?
2, 4, 6, 8 …
These numbers come out

What is happening?
Numbers are entered into a function machine
1, 2, 3, 4 …
2, 3, 4, 5 …
These numbers come out

What is happening?
Numbers are entered into a function machine
10, 20, 30, 40 …
5, 10, 15, 20 …
These numbers come out

Using the TI15 Explorer™
• Locate the op1 key 
• This key operates like a function machine.
• To simulate a function machine that doubles the numbers press  x2  .
• Enter 5 into your calculator press  .
The display should show 10.

Using the TI15 Explorer™ 2
• Use the  key to create your own function machine questions.
• Write your questions on the single function machine worksheet.
• Remember to keep a copy of your questions and answers.
• Give a copy of your question sheet to a partner to solve.

Reverse Function Machine
What happens if the function machine is set in reverse?
1, 2, 3, 4 ….
What is happening to the numbers?
2, 4, 6, 8 …
These numbers are fed into the machine

Reverse Function Machine 2
What happens if the function machine is set in reverse?
1, 2, 3, 4 ….
What is happening to the numbers?
2, 3, 4, 5 …
These numbers are fed into the machine

Reverse Function Machine 3
What happens if the function machine is set in reverse?
10, 15, 20, 25 ….
20, 30, 40, 50 …
These numbers are fed into the machine
What is happening to the numbers?

Linking Forward and Reverse
• What do you notice happens to the operation when a function machine is set in reverse?
• Explore your ideas using the  key on your
TI15 Explorer™ calculator

Forward and Reverse
• + and – are inverse operations
If the function machine adds 2, then when it is put in reverse it would subtract 2
• X and ÷ inverse operations
If the function machine multiplies by 10, then when it is put in reverse it will divide by 10

What Happens When Two Function
Machines Are Joined?
1, 2, 3, 4 ….
+ 2
+ 3
Test it out using the  and  keys on your
TI15 Explorer™ calculator

Addition and Subtraction
1, 2, 3, 4 ….
+ 5
– 2
What about subtracting and adding?

Multiplication
1, 2, 3, 4 ….
x 2 x 5
Could I replace two function machines with one machine?
What single machine could replace the two machines?

Multiplication and Division
1, 2, 3, 4 ….
x 10
÷
2
What happens when you join two division function machines?

43
49
55
61
67
73
79
7
13
19
25
31
37
103
109
115
85
91
97
105
111
117
87
93
99
57
63
69
75
81
27
33
39
45
51
3
9
15
21
Prime Numbers
104
110
116
86
92
98
56
62
68
74
80
26
32
38
44
50
2
8
14
20
88
94
100
106
112
118
58
64
70
76
82
28
34
40
46
52
4
10
16
22
89
95
101
107
113
119
59
65
71
77
83
29
35
41
47
53
5
11
17
23
90
96
102
108
114
120
60
66
72
78
84
30
36
42
48
54
6
12
18
24

68
74
80
86
92
98
104
110
116
2
8
14
20
26
32
38
44
50
56
62
67
73
79
85
91
97
103
109
115
1
7
13
19
25
31
37
43
49
55
61
70
76
82
88
94
100
106
112
118
4
10
16
22
28
34
40
46
52
58
64
69
75
81
87
93
99
105
111
117
3
9
15
21
27
33
39
45
51
57
63
72
78
84
90
96
102
108
114
120
6
12
18
24
30
36
42
48
54
60
66
71
77
83
89
95
101
107
113
119
5
11
17
23
29
35
41
47
53
59
65