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quarters, dimes, nickels, and pennies it takes to make that amount. As many high-

er-valued coins as possible should be used. For example, for the amount $4.20,

the program should print on one line:

16 quarters, 2 dimes, 0 nickels, and 0 pennies

E18.
Write a function that is given the number of seconds from midnight and

returns a String that contains the number of hours, minutes, and seconds from

midnight that it represents, suitably annotated. For example, called with argu-

ment
3675
, it yields
"1 hour 1 minute 15 seconds"
.

E19.
Write a procedure that is given the number of seconds from midnight and

prints the number of hours, minutes, and seconds from midnight that it repre-

sents, suitably annotated. For example, called with argument
3675
, this should

be printed:
1 hour 1 minute 15 seconds
.

E20.
Write a function that is given a time in terms of hours, minutes, and sec-

onds and returns the time in seconds only (as an integer). This is, in a sense, the

inverse of the previous exercise. For example, for 1 hour, 1 minute and 15 sec-

onds, return the integer
3676
.

E21.
Write a function that is given two times in military format and prints the

hours and minutes between the two times. You may assume that the second

parameter is the bigger of the two. For example, for the arguments (0352, 1900)

—that is 3:52AM and 7:00P— the result is:
15 hours 8 minutes
. To make

things easier for you, try doing it by calling the function and procedure of the

previous two exercises.

E22.
Write a function with an
int
parameter whose value is in the range
0..15

and that returns a
String
of length 4 that depicts its binary equivalent. For

example, for the number
7
, the answer is the
String "0111"
. Here is a hint. The

rightmost bit is
7%2
, and the first three bits are the binary representation of
7/2
.

E23.
Write a procedure with an
int
parameter whose value is in the range
0..15

and that prints its binary equivalent. For example, for the number
7
, this should

be printed:
0111
. Here is a hint. The rightmost bit is
7%2
, and the first three bits

are the binary representation of
7/2
.

E24.
In Sec. 0.1, near Fig. 0.2, we outlined the relationship between the decimal,

hexadecimal, octal, and binary numbers systems. Write a procedure that prints

the first 7 natural numbers (
0, 1, 2, ..., 8
) in all four systems. The first line

should contain 0 in all four systems; the second; 1 in all four systems; and so on.

For descriptions of static methods to help you do this exercise, turn to lesson

page 5-1 of the CD and click on the footnote for static methods of class
Integer

(near activity 3).

E25.
Do the same as for the previous exercise, but print the decimal values 21,

22, 23, 24, 25 in each of the four number systems.

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