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Class 8

Math riddles for class 8

CLASS 8 RIDDLES

  1. I am a number less than 100. I am a multiple of 7 and also a multiple of 8. What number am I?
  2. What is the only number that, when multiplied by itself, gives the same result when added to itself?
  3. I have four sides, all equal. I am not a square. What am I?
  4. What has three faces, all of which are squares?
  5. What has no end, beginning, or corners?
  6. If you divide me by 2, you get one number. If you divide me by 3, you get a different number. If you divide me by 5, you get yet another number. I am between 20 and 30. What number am I?
  7. Two fathers and two sons went fishing. They caught exactly three fish. How is this possible?
  8. What is heavier, a pound of feathers or a pound of bricks?
  9. What has one voice, but can make many sounds, and sometimes tells stories?
  10. What has cities, mountains, and water, but no houses, trees, or fish?
  11. What is always in front of you but can’t be seen?
  12. What has to be broken before you can use it?
  13. What is always coming, but never arrives?
  14. What is full of holes but can still hold water?
  15. What has one head, one foot, and four legs?
  16. I am a number. If you subtract 8 from me, you get the same result as if you divide me by 3. What number am I?
  17. I am a shape with six faces, all of which are rectangles. What am I?
  18. I am a number that is a perfect square and a perfect cube. I am less than 100. What number am I?
  19. What has no weight but can still be measured?
  20. You can keep me after giving me to someone else. What am I?

Problems for class 8 to test your knowledge in maths

CLASS 8 SUMS

  1. Ten years ago, a father’s age was three times his son’s age. Ten years from now, the father’s age will be twice the son’s age. Find their present ages.
  2. A can do a piece of work in 12 days. B can do the same work in 20 days. How long will it take them to do the work together?
  3. A rectangular garden is 10 meters long and 8 meters wide. A path of uniform width is built around the garden. If the area of the path is 112 square meters, find the width of the path.
  4. A cylindrical container has a radius of 7 cm and a height of 10 cm. How many litres of water can it hold? (Use π = 22/7)
  5. Find the smallest number that is exactly divisible by both 12 and 18.
  6. A shopkeeper sells two articles, one at a loss of 10% and the other at a profit of 15%, but finally there is no gain or no loss. If the total sale price of these two articles is Rs. 10,000, find the cost price of each article.
  7. How many kilograms of rice at Rs. 9.30 per kg must be mixed with 10 kg of rice at Rs. 10.80 per kg so that the mixture can be sold at Rs. 10.20 per kg to produce a 15% profit?
  8. Ten years ago, a father was seven times as old as his son. In ten years’ time, he will be twice as old as his son. What are their present ages
  9. The sum of the digits of a two-digit number is 12. If the digits are reversed, the new number is greater than the original number by 54. Find the original number.
  10. A can do a piece of work in 10 days, and B can do it in 15 days. How many days will they take to complete the work together?
  11. A and B together can do a piece of work in 12 days. B and C together can do it in 15 days. A and C together can do it in 20 days. In how many days can each do it alone?
  12. A cistern can be filled by one pipe in 5 hours and by another pipe in 6 hours. How long will it take to fill the cistern when both pipes are opened together?
  13. A train travels a distance of 300 km at a uniform speed. If the speed had been 5 km/hr more, it would have taken 2 hours less for the same journey. Find the speed of the train.
  14. A boat goes 24 km upstream and 36 km downstream in 6 hours. Also, it covers 36 km upstream and 24 km downstream in 6.5 hours. What is the speed of the boat in still water and the speed of the stream
  15. A shopkeeper sells two articles at Rs. 1000 each. On one, he gains 10% and on the other, he loses 10%. Find his overall gain or loss percentage.
  16. A person sells an article at a loss of 10%. Had he sold it for Rs. 75 more, he would have gained 5%. For how much did he purchase it?
  17. A sum of money at simple interest amounts to Rs. 815 in 3 years and to Rs. 854 in 4 years. The sum is: ??
  18. What will be the compound interest on a sum of Rs. 10,000 at 10% per annum for 3 years
  19. Divide Rs. 6000 among A, B, and C so that A receives one-half of the sum of what B and C receive.
  20. How many kg of rice at Rs. 9 per kg must be mixed with 25 kg of rice at Rs. 10 per kg so that the mixture can be sold at Rs. 9.80 per kg to earn a profit of 20% on the cost?
  21. The angles of a triangle are in the ratio 2:3:4. Find the measure of each angle.
  22. The sides of a triangle are in the ratio 3:4:5. Find the angles of the triangle.
  23. The length of a rectangle is increased by 50% and its breadth is decreased by 25%. Find the percentage change in its area.
  24. The volume of a cube is 1728 cubic cm. Find the surface area of the cube.
  25. If x + 1/x = 5, find the value of x^2 + 1/x^2.
  26. If a + b + c = 0, prove that a^3 + b^3 + c^3 = 3abc.
  27. The mean of 5 numbers is 27. If one number is excluded, their mean becomes 25. Find the excluded number.

Tentative math syllabus of class 8

Class 8 math syllabus

Key Topics:

Rational Numbers:

    • Properties and operations of rational numbers.
    • Representation on the number line.

Linear Equations in One Variable:

    • Solving linear equations.
    • Applications in word problems.

Understanding Quadrilaterals:

    • Types and properties of quadrilaterals.
    • Angle sum property.

Data Handling:

    • Bar graphs, pie charts, histograms.
    • Probability.

Squares and Square Roots:

    • Finding squares and square roots.
    • Applications.

Cubes and Cube Roots:

    • Finding cubes and cube roots.

Comparing Quantities:

    • Percentages, profit and loss, compound interest.

Algebraic Expressions and Identities:

    • Operations on algebraic expressions.
    • Standard algebraic identities.
    • Factorization.

Mensuration:

    • Area and perimeter of plane figures.
    • Surface area and volume of solid shapes.

Exponents and Powers:

    • Laws of exponents.

Direct and Inverse Proportions:

    • Applications of direct and inverse proportions.

Factorisation:

    • Factorizing algebraic expressions.

Introduction to Graphs:

    • Introduction to coordinate geometry.
    • Linear graphs.