Percentage Badhe-Ghate (SSC CGL Maths)

Is topic me hum bilkul desi style me samjhenge ki % badhta kaise hai aur % ghatta kaise hai. Saath me formula, rule, aur SSC wale short tricks bhi.

1) Percentage Change ka matlab

Kisi cheez ki value badhe ya ghate, to uska change ko % me bolte hain.
Base hamesha purani value (Original) hoti hai.

% Change = (Change / Original) × 100

Change = New − Old
Original (Old) = pehle wali value (base)

Short Trick: “% nikalna hai to hamesha purane par divide.”

2) Seedha Formula (Fast)

Case	Formula	Short Trick
p% Badhe	New = Old × (1 + p/100)	Old ko (100+p)/100 se guna
p% Ghate	New = Old × (1 − p/100)	Old ko (100−p)/100 se guna
% Badha kitna?	p = (New−Old)/Old × 100	“Fark ÷ purana × 100”
% Ghata kitna?	p = (Old−New)/Old × 100	“Fark ÷ purana × 100”

Super Tip: Agar 20% increase hai to factor 1.2, aur 20% decrease hai to factor 0.8.

3) SSC ke Top Rules (Must Remember)

Rule A: +x% aur phir −x% (same percent)
Net % = −(x²/100)

Short Trick: Same % up-down = hamesha loss. “Square karke 100 se divide, minus laga do.”

Example: +10% then −10% ⇒ −(10²/100)= −1%
Rule B: Do changes a% aur b%
Net % = a + b + (ab/100)

Short Trick: “Pehle add, phir multiply, 100 se divide.” (decrease ko negative lo)
Rule C: Reverse Percentage (ulta nikalna)
Old = New ÷ (1 + p/100) (increase)

Old = New ÷ (1 − p/100) (decrease)

Short Trick: New given hai to “factor se divide” karke purana nikaal lo.

4) Desi Solved Examples (Jaldi Samajh)

Example 1: 25% Badhao

Q: 800 ka 25% badhao. New?

New = 800 × 1.25 = 1000

Trick: 25% = 1/4, to 800 ka 1/4 = 200, add ⇒ 1000

Example 2: 15% Ghatao

Q: 1200 ka 15% ghatao. New?

New = 1200 × 0.85 = 1020

Trick: 15% ghataya = 85% bacha ⇒ 1200 ka 85%.

Example 3: 20% up, 10% down

Q: Price 20% badha, phir 10% ghata. Net?

Net = 20 + (−10) + (20×−10)/100 = 10 − 2 = 8% increase

Trick: Factor: 1.2 × 0.9 = 1.08 ⇒ 8% up

Example 4: Reverse (ulta)

Q: 20% badhne ke baad price 600 ho gaya. Purana?

Old = 600 ÷ 1.2 = 500

Trick: 1.2 = 6/5 ⇒ divide by (6/5) means multiply by (5/6): 600×5/6=500

5) 1-Minute Short Tricks Sheet

Increase p% ⇒ multiply by (100+p)/100
Decrease p% ⇒ multiply by (100−p)/100
New given ⇒ Old = New ÷ factor
Same % up-down ⇒ loss x²/100
Two changes ⇒ a + b + ab/100
Fast factors: 10%=1.1/0.9, 20%=1.2/0.8, 25%=1.25/0.75, 50%=1.5/0.5

6) Practice (SSC Type)

500 ka 12% badhao. New?
2400 ka 18% ghatao. New?
Salary 10% badhi aur phir 10% ghati. Net change?
Price 25% ghata aur new price 750 hai. Original?
Quantity 20% badhi aur price 10% ghata. Total kharcha (expenditure) me net %?

Short Tip: Expenditure = Price × Quantity. Factor method use karo: (1±p/100) × (1±q/100).