ANSWERS
TO
SELF
TEST
ON
CHAPTER
2
1.
2.
An
internal number
store
is
like
a pigeon hole which
you
can name and put
numbers
Into.
A LET
statement
which uses a particular name
for
the
first
time
will
cause a pigeon
hole
to
be created and named, for example
•
LET count = 1
..
"
(1
point)
CHECK
YOUR
SCORE
A READ statement which
uses
a name for the
first
time
will
have the same
effect,
for
example
READ count
..
"
(1
point)
3.
You
can find the value
of
a pigeon hole with a PRINT statement
4.
The technical name
for
a pigeon hole
is
variable' because
its
values can vary
as
a program
runs.
5.
A variable
gets
its
first
value
when
it
is
first
used
in
a LET
statement,
INPUT
statement
or READ
statement.
6.
A change
in
the
value
of
a variable
is
usually caused by the execution
of
a LET
statement.
7.
The
= sign
In
a LET statement represents
an
operation:
'Evaluate whatever
is
on the right hand side and place
it
in
the pigeon hole
named on the
left
hand
side,
that
is
'Let
the
left
hand side become equal
to
the right hand
side:
8.
An
un-numbered statement
is
executed immediately.
9.
A numbered statement
is
not executed immediately.
It
is
stored.
10.
The quotes
in
a PRINT statement enclose
text
which is
to
be printed.
11.
When quotes
are
not used you
are
printing out the value
of
a variable.
12.
An
INPUT statement makes the program pause
so
that
you
can type data
at
the
keyboard.
13.
DATA
statements are never executed.
14.
They
are used
to
provide values for the variables
in
READ
statements.
15.
The technical word for the name
of
a pigeon hole
is
'identifier:
16.
Example
answers:
i.
day
ii
day_23
iii
day_of_week
(3
points)
17.
The space bar
is
especially important for putting spaces after or before keywords
so
that they cannot be taken
as
identifiers (names) chosen by the user
18.
Freely
chosen identifiers
are
important because they help
you
to
make programs
easier
to
understand. Such programs
are
less
prone
to
errors and more adaptable.
18
to
21
is
very good.
Carryon
reading.
16
or
17.
good but re-read some parts
of
chapter
two.
14
or
15
fair,
but re-read some parts
of
chapter
two
and
do
the
test
again.
Under
14
you
should work carefuly through chapter
two
again and repeat the
test.
1?IR4
•
'.
•
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