Ganita Prakash Part-II, Grade 8, Textbook of Mathematics – Chapter 6 in NCERT book Ganita Prakash Part-II, Algebra Play is one of the most important chapters in class 8. In this chapter’s worksheet, you are going to solve problems related to the below topics –
- Number trick patterns
- Algebra using variables
- Pyramid sum puzzles
- Calendar grid algebra
- Logic and equations
The questions in this worksheet is broken down into 4 parts – Basic, Standard, Advance, and HOTS. The answers is also there at the end.
Class 8 Maths Worksheet – Chapter 6: Algebra Play
Basic
-
Think of a number trick:
Think of a number. Triple it. Add 6. Divide by 3. Subtract the original number.
What answer do you always get? -
Modify the previous trick so that the final answer is always 3.
(Write the new steps.) -
Date trick (decode the date):
Someone follows the date steps from the chapter and tells you the final answer is 1269.
What date did they think of? (Write as DD/MM) -
Number pyramid:
In a 3-row pyramid, each box is the sum of the two boxes directly below it.
If the bottom row is 3, 4, 3, what number is at the top? -
Calendar magic (2×2 grid):
In a calendar, a 2×2 grid has sum 52.
Find the four numbers in the grid. -
Reverse-and-subtract trick:
Start with 47. Reverse to get 74. Subtract the smaller from the larger. Divide by 9.
What quotient do you get?
Standard
-
Always-5 trick (design):
Create a “think of a number” trick that always ends in 5 using exactly these operations:
Multiply → Add → Divide → Subtract original number.
Write your steps clearly. -
Date trick (decode):
Final answer reported is 296.
Find the date (DD/MM). -
Number pyramid (missing middle):
Top is 50. Bottom row is 4, x, 6.
Find x and complete the pyramid. -
Calendar magic (2×2 grid):
The sum of a 2×2 calendar grid is 68.
Find the four numbers. -
Algebra grid (shapes):
Let square = s, triangle = t, circle = c.
Given:- s + t + c = 27
- 2s + c = 21
- t + 2c = 18
Find s, t, and c.
-
Largest product:
Use the digits 3, 5, 9 exactly once in __ __ × __.
Find the largest possible product.
Advance
-
Cyclic digits (divisible by 37):
Take 258. Form 258, 582, and 825 and add them.
Find the sum and check if it is divisible by 37. -
abcabc trick:
Take abc = 246. Form abcabc = 246246.
Divide it by 7, then by 11, then by 13. What do you get? -
Three shrines, three ponds:
A person starts with some flowers.
At each pond, the flowers double. After pond 1 he places some flowers in shrine 1.
After pond 2 he places the same number in shrine 2.
After pond 3 he places all remaining flowers in shrine 3.
If each shrine gets the same number of flowers, find:- How many flowers did he start with?
- How many flowers in each shrine?
-
Heads and legs:
A farm has horses and hens. Total heads = 55, total legs = 150.
Find the number of horses and hens. -
Mother-daughter ages:
A mother is 5 times her daughter’s age.
In 6 years, the mother will be 3 times her daughter’s age.
Find the daughter’s present age. -
Dosa cart profit:
Rent is ₹5000 per day and the cost of making one dosa is ₹10.- If 100 dosas are sold, what should be the selling price per dosa to make profit ₹2000?
- If customers pay only ₹50 per dosa, how many dosas must be sold to make profit ₹2000?
HOTS
-
Calendar formula:
In a 2×2 calendar grid, let the top-left number be a.
The grid is:
a, a+1
a+7, a+8
Show that the sum is 4a + 16.
If the sum is 92, find the four numbers. -
Largest product (general rule):
Digits p, q, r satisfy p < q < r.
You must place them in __ __ × __.
Which arrangement gives the largest product? (Write the arrangement and one-line reason.) -
Reverse-and-add trick:
Take any 2-digit number ab (a ≠ b). Reverse it to ba and add:
(10a + b) + (10b + a)
Show the sum is always divisible by 11. -
Fraction pattern:
Evaluate:
1/3, (1+3)/(5+7), (1+3+5)/(7+9+11)
What do you observe? Explain in 2–3 lines why it happens. -
Genie deal:
Karim goes around a tree 3 times.
Each time, his coins double, and then he must give the genie 8 coins.
After the third round, he has exactly 8 coins left (and he still owes 8).
How many coins did Karim have at the start? -
Invent your own trick:
Create a “think of a number” trick that always ends in 7.
Write the steps and also write a short algebra proof using x.
Answer Key
Basic – Answers
-
Ans: 2
Hint: Let the number be x: 3x → 3x+6 → (3x+6)/3 = x+2 → (x+2)−x = 2. -
Ans (one example): Triple it → Add 9 → Divide by 3 → Subtract original → always 3
Hint: 3x+9 → (3x+9)/3 = x+3 → (x+3)−x = 3. -
Ans: 04/11 (4th November)
Hint: Subtract 165: 1269 − 165 = 1104 = 100M + D ⇒ M=11, D=04. -
Ans: 14
Hint: Middle row: 3+4=7 and 4+3=7, top: 7+7=14. -
Ans: 9, 10, 16, 17
Hint: Sum = 4a+16. So 4a+16=52 ⇒ a=9. -
Ans: 3
Hint: 74−47=27, 27/9=3.
Standard – Answers
-
Ans (one example):
Multiply by 4 → Add 20 → Divide by 4 → Subtract original → always 5
Hint: 4x+20 → (4x+20)/4 = x+5 → (x+5)−x = 5. -
Ans: 31/01 (31st January)
Hint: 296 − 165 = 131 = 100M + D ⇒ M=1, D=31. -
Ans: x = 20
Pyramid: Middle row: 24 and 26; Top: 50
Hint: Top = (4+x) + (x+6) = 2x+10 = 50. -
Ans: 13, 14, 20, 21
Hint: 4a+16=68 ⇒ a=13. -
Ans: s = 10, t = 16, c = 1
Hint: From 2s+c=21 ⇒ c=21−2s. Substitute into others. -
Ans: 53 × 9 = 477
Hint: Put the largest digit as the multiplier (9), and arrange the other two as 53.
Advance – Answers
-
Ans: 258+582+825 = 1665, and 1665 ÷ 37 = 45
Hint: Check 37×45 = 1665. -
Ans: 246
Hint: 246246 = 1001×246 and 1001 = 7×11×13. -
Ans: Start with 7 flowers, each shrine gets 8
Hint: Try smallest number that makes equal sharing possible; check by working backward. -
Ans: Horses = 20, Hens = 35
Hint: 4h + 2(55−h) = 150. -
Ans: Daughter = 6 years
Hint: 5d+6 = 3(d+6). -
Ans:
- Selling price = ₹80
- Required dosas = 175
Hint: Profit = Revenue − (Rent + Making cost).
HOTS – Answers
-
Ans: Sum = 4a+16.
If sum=92: 4a+16=92 ⇒ a=19.
Grid: 19, 20, 26, 27 -
Ans: Largest product is qp × r
Reason: Use the largest digit as multiplier and make the 2-digit number as large as possible. -
Ans: (10a+b)+(10b+a)=11(a+b), so divisible by 11
Hint: Factor 11 out. -
Ans: All are 1/3
Hint: (1+3+…+(2n−1)) = n² and (5+7+… up to n terms) = 3n², so ratio = n²/(3n²)=1/3. -
Ans: 7 coins
Hint: After 3 rounds: start N.
After round1: 2N−8
After round2: 2(2N−8)−8 = 4N−24
After round3: 2(4N−24) = 8N−48 equals 8 ⇒ N=7. -
Ans (one example):
Multiply by 5 → Add 35 → Divide by 5 → Subtract original → always 7
Proof: Start x → 5x → 5x+35 → (5x+35)/5 = x+7 → (x+7)−x = 7.
Worksheet From Other Chapters
Ganita Prakash Part-I
- A Square and a Cube Class 8 Maths Worksheet with Answers
- Power Play Class 8 Maths Worksheet with Answers
- A Story of Numbers Class 8 Maths Worksheet with Answers
- Number Play Class 8 Maths Worksheet with Answers
- We Distribute, Yet Things Multiply Class 8 Maths Worksheet with Answers
- Proportional Reasoning-1 Class 8 Maths Worksheet with Answers