A discount series of 10%, 20% and 40% is equal to single discount of ?

Let original price = Rs. 100 Price after 1 st discount = Rs. 90 Price after 2 nd discount = Rs. (80/100) x 90 = Rs. 72 Price after 3 rd discount = Rs. (60/100) x 72 = Rs. 43.20 ∴ Single equivalent discount = (100 - 43.20) = 56.8%