mb(TDS)Ti89, hp '42S,35S'35, Code'Operatio' Exampl 'RPN'[SWAP Stack X<=>Y(►'STO' @ hp 50G:49G)or Comma Key @ hp Prime],Tuto

9 + 8 + 7 – (6) = 18
(i)
6
ENTER
9
ENTER
8
+
7
+
x<>y
–
Answer:
18
(ii)
6
ENTER
CHS
7
+
8
+
9
+
(iii)
6
ENTER
CHS
9
+
8
+
7
+
(iv)
6
ENTER
7
x<>y
–
8
+
9
+
Answer:
18
Answer:
18
Answer:
18
9 + 8 – 7 – (6) = 4
(i)
6
ENTER
9
ENTER
8
+
7
–
x<>y
–
Answer:
4
(ii)
6
ENTER
CHS
7
CHS
+
8
+
9
+
Answer:
4
9 + 8 – 7 + (6) = 16
(i)
6
ENTER
9
ENTER
8
+
7
–
+
Answer:
16
(ii)
6
ENTER
7
CHS
+
8
+
9
+
Answer:
16
9 – 8 + 7 + (6) = 14
(i)
6
ENTER
9
ENTER
8
–
7
+
+
Answer:
14
(A)
(ii)
6
ENTER
7
+
8
CHS
+
9
+
Answer:
14
(B)
(iii)
6
ENTER
CHS
7
–
8
+
9
+
(iv)
6
ENTER
CHS
9
+
8
+
7
–
Answer:
4
Answer:
4
(v)
6
ENTER
7
CHS
x<>y
–
8
+
9
+
Answer:
4
(vi)
6
ENTER
7
x<>y (wrong!)
–
8
x<>y (wrong!)
–
9
+
Answer:
16 (wrong!)
(C)
(iii)
6
ENTER
7
–
8
+
9
+
(iv)
6
ENTER
9
+
8
+
7
–
Answer:
16
Answer:
16
(v)
6
ENTER
7
+ (wrong!)
8
x<>y (wrong!)
–
9
+
Answer:
4 (wrong!)
(D)
(iii)
6
ENTER
7
+
8
–
9
+
(iv)
6
ENTER
9
+
8
–
7
+
Answer:
14
Answer:
14
(v)
6
ENTER
7
+
8
+ (wrong!)
9
x<>y (wrong!)
–
Answer:
–12 (wrong!)