Given: A number increases by 25% if 60 is added to it. Formula: Percentage increase = (new - actual)/actual × 100 Calculation: Let the number be x. ⇒x+0.25x=x+60 ⇒x=60×4=240 New number =240+600=840 Percentage increase =(840–240)/(240)×100 ⇒(600/240)×100 ⇒250 ∴ The number should increase by 250%.