Question 9 - Figure it out - Page 19, 20 - Chapter 1 Class 8 - Fractions in Disguise (Ganita Prakash II)

Last updated at February 13, 2026 by

[Class 8] A number increased by 20% becomes 90. What is the number? - Figure it out - Page 19, 20

part 2 - Question 9 - Figure it out - Page 19, 20 - Chapter 1 Class 8 - Fractions in Disguise (Ganita Prakash II) - Class 8 (Ganita Prakash - 1, 2 & Old NCERT)
part 3 - Question 9 - Figure it out - Page 19, 20 - Chapter 1 Class 8 - Fractions in Disguise (Ganita Prakash II) - Class 8 (Ganita Prakash - 1, 2 & Old NCERT)

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Question 9 A number increased by 20% becomes 90. What is the number?Now, Percentage increase = π‘ͺπ’‰π’‚π’π’ˆπ’†/(π‘Άπ’“π’Šπ’ˆπ’Šπ’π’‚π’ π’π’–π’Žπ’ƒπ’†π’“) Γ— 100 Given Percentage increase = 20% Increased number = 90 We need to find Original number Now, Percentage increase = πΆβ„Žπ‘Žπ‘›π‘”π‘’/(π‘‚π‘Ÿπ‘–π‘”π‘–π‘›π‘Žπ‘™ π‘›π‘’π‘šπ‘π‘’π‘Ÿ) Γ— 100 Percentage increase = (𝑰𝒏𝒄𝒓𝒆𝒂𝒔𝒆𝒅 π’π’–π’Žπ’ƒπ’†π’“ βˆ’ π‘Άπ’“π’Šπ’ˆπ’Šπ’π’‚π’ π’π’–π’Žπ’ƒπ’†π’“)/(π‘Άπ’“π’Šπ’ˆπ’Šπ’π’‚π’ π’π’–π’Žπ’ƒπ’†π’“) Γ— 100 Putting values 20 = (πŸ—πŸŽ βˆ’ π‘Άπ’“π’Šπ’ˆπ’Šπ’π’‚π’ π’π’–π’Žπ’ƒπ’†π’“)/(π‘Άπ’“π’Šπ’ˆπ’Šπ’π’‚π’ π’π’–π’Žπ’ƒπ’†π’“) Γ— 100 20/100 = (90 βˆ’ π‘‚π‘Ÿπ‘–π‘”π‘–π‘›π‘Žπ‘™ π‘›π‘’π‘šπ‘π‘’π‘Ÿ)/(π‘‚π‘Ÿπ‘–π‘”π‘–π‘›π‘Žπ‘™ π‘›π‘’π‘šπ‘π‘’π‘Ÿ) 𝟏/πŸ“ = (πŸ—πŸŽ βˆ’ π‘Άπ’“π’Šπ’ˆπ’Šπ’π’‚π’ π’π’–π’Žπ’ƒπ’†π’“)/(π‘Άπ’“π’Šπ’ˆπ’Šπ’π’‚π’ π’π’–π’Žπ’ƒπ’†π’“) Cross-multiplying 1 Γ— Original number = 5 Γ— (90 – Original number) Original number = 5 Γ— 90 – 5 Γ— Original number Original number = 450 – 5 Γ— Original number Original number + 5 Γ— Original number = 450 6 Γ— Original number = 450 Original number = πŸ’πŸ“πŸŽ/πŸ” Original number = 150/2 Original number = 75 Thus, original number is 75

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CA Maninder Singh is a Chartered Accountant for the past 16 years. He also provides Accounts Tax GST Training in Delhi, Kerala and online.