Crack Java Math Problems

Before we start attempting the questions on Java Math class, lets do a quick revision on Java libraries and Math class in particular.

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Lets Start!

1. In which package is math class located in Java?

Ans: Java.lang package.

2. What is the return type of following Java math functions
   1. round(3.14)
   2. pow()
   3. rint()
   4. sqrt()

Ans:

1. 1. long
   2. double
   3. double
   4. double

3. What is the return type of following Java math functions
   1. sin()
   2. ceil()
   3. round((float)x);
   4. exp()

Ans:

1. 1. double
   2. double
   3. int
   4. double

4. Answer the questions
   1. What is the range of value returned by random() function
   2. What is the return type of random() function.

Ans:

1. 1. greater than or equal to 0.0 and less than 1.0  or  random no >= 0 and random no < 1.
   2. double

5. Answer the questions
   1. Write a Java statement to generate a random number from 1 – 10.
   2. Write a Java statement to generate a random number to simulate a dice.

Ans:

1. 1. (int)(Math.random() * 10) + 1;
   2. (int)(Math.random() * 6) + 1;

6. Give the output of the following:

(i) Math.floor(-4.7) (ii) Math.ceil(3.4) + Math.pow(2, 3)

Ans.

i) -5.0 ii) 12.0     Explanation: 4.0 + 8.0

7. What are the values stored in variables r1 and r2:
   1. double r1 = Math.abs(Math.min(-2.83,-5.83));
   2. double r2 = Math.sqrt(Math.floor(16.3));

Ans.

1. 1. double r1 = Math.abs(Math.min(-2.83,-5.83)); = Math.abs(-5.83) = 5.83

1. 1. double r2 = Math.sqrt(Math.floor(16.3)); = Math.sqrt(16) = 4.0

8. What will be the output of the following function?

i) Math.pow(9,0.5)               ii) Math.min(-21,-12) iii) Math.ceil(5.2)                 iv) Math.floor(2.9)

Ans   i) 3.0             ii) -21               iii) 6.0                  iv) 2.0

9. Give the output of the following Math functions:

(i) Math.ceil(4.2) (ii) Math.abs(-4)

Ans.

(i) 5.0 (and not 5, as ceil() returns a double) (ii) 4

10. Give the result of the following functions:

1. 1. Math.floor(70.3)
   2. Math.ceil(-10.01)
   3. Math.sqrt(36)
   4. Math.abs(-9)

Ans.

1. 1. 70.0
   2. -10.0
   3. 6.0
   4. 9

11. What is the value stored in x and y after execution of these statements?

double x = Math.ceil(8.3) + Math.floor(-3.2)+Math.rint(4.5); double y = Math.abs(Math.round(Math.max( -4.4, -9.6)));

Ans.

X = 9.0 Working: 9.0 + (-4.0) + 4.0 = 9.0 Y = 4.0 Working Math.abs(Math.round(-4.4)) = 4.0

12. What is the output of following statements?

double d1 = -0.5d; System.out.println(“Ceil for dl= ” + Math.ceil( dl ); System.out.println(“Floor for dl= ” +Math.floor (d1 ));

Ans:

Ceil for d1= -0.0 Floor for d1= -1.0;

13. What are the final values stored in variables x and y below?

double a = – 6.35; double b = 14.74; double x = Math.abs(Math.ceil(a)); double y = Math.rint(Math.max(a,b));

Ans.

x=6.0 and y=15.0

14. What are the values stored in variables r1 and r2:

(i) double r1 = Math.abs(Math.min(-2.83,-5.83)); (ii) double r2 = Math.sqrt(Math.floor(16.3));

Ans.

1. 1. (i) r1=5.83 (ii) r2=4.0

15. Give the output of the following:

a) Math.floor (-4.7) b) Math.ceil(3.4) + Math.pow(2, 3)

Ans.

1. 1. a) -5.0 b) 12.0

16. Give the results of the following functions:

(i) Math.floor (81.2)

(ii) Math.ceil (-10.01)

(iii) Math.sqrt (25)

(iv) Math.cbrt (-27.0)

Ans:

(i)81.0       (ii) -10.0       (iii) 5.0        (iv) -3.0

17. Give the output of the following:

i. Math.ceil(4.2) ii. Math.abs(-4)

Ans.

i. 5.0 ii. 4

18. Give the output of the following:
    1. Math.max(-17, -19)
    2. Math.ceil(7.8)

Ans.

1. 1. -17
   2. 0

19. Give the output of the following:
    1. Math.floor(15.36)
    2. Math.round(146.5)

Ans.

1. 1. 15.0
   2. 147

20. Give the output of the following:
    1. Math.max(11,10)
    2. Math.ceil(-12.56)

Ans.

1. 1. 11
   2. -12.0

21. Give the output of the following:
    1. Math.sqrt(625)
    2. Math.cbrt(125)

Ans.

1. 1. 25.0
   2. 5.0

22. Give the output of the following:
    1. Math.min(-0.0,0.0)
    2. Math.pow(4,3)

Ans.

1. 1. -0.0
   2. 64.0

23. Give the output of the following:
    1. Math.floor(-126.349)
    2. Math.max(45.6,17.3)

Ans.

1. 1. -127.0
   2. 45.6

24. What are the final values stored in variables x and y below?

double a = – 6.35; double b = 14.74; double x = Math.abs(Math.ceil(a)); double y = Math.rint(Math.max(a,b));

Ans.

Math.ceil() gives the smallest of all those integers that are greater than the input. So, Math.ceil(-6.35) gives -6.0 (not -6 as ceil returns a double value). Math.abs() gives the absolute value of the number i.e. removes negative sign, if present. So, Math.abs(-6.0) results in 6.0. So, x = 6.0.

Math.max(-6.35, 14.74) returns 14.74. rint() returns the double value which is closest in value to the argument passed and is equal to an integer. So, Math.rint(14.74) returns 15.0. So, y = 15.0.