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Word Problem on Estimation (Page 10)
Last updated at July 30, 2025 by Teachoo
Estimating Square Root
Class 8 (Ganita Prakash & Old NCERT)
Chapter 1 Class 8 - A Square and a Cube (Ganita Prakash)
- Introduction
- Square Numbers
- Perfect Squares - and its Properties
- Perfect Squares - and its Patterns
- Square Root
- Smallest number multiply or divide to get perfect square
-
Estimating Square Root
- Figure it out - Page 10, 11
- Cubic Numbers
- Perfect Cubes - and its Properties
- Perfect Cubes - and its Patterns
- Cube Root
- Smallest number multiply or divide to get perfect cube
- A pinch of History
- Figure it out - Page 16, 17
Transcript
Word Problem on Estimation (Page 10) Akhil has a square piece of cloth of area 125 cm2. He wants to know if he can cut out a square handkerchief of side 15 cm. If not, he wants to know the maximum size handkerchief that can be cut out from this piece of cloth with an integer side length. Let Side of Handkerchief = a Now, Max Area of Handkerchief = 125 cm2 a2 = 125 a = √125 We need to find √125, let’s find it by estimation Finding √𝟏𝟐𝟓 using estimation We know 102 = 100 and 122 = 144. So, the root is between 10 and 11. Now, 112 = 121 – which is very close to 125 Thus, √𝟏𝟐𝟓 is approximately 11 Since the cloth's area is 125 cm², he cannot cut out a square of area 144 cm² (which would require a 12 cm side). The largest perfect square area he can use is 121 cm². The largest square handkerchief that can be cut from the piece of cloth has a side length of 11 cm
