If 1apples are bought at rs 10 and 10 apples are at rs 11. what is the gain%.?

1 apple cost Rs 10, and 10 apples are at Rs11.

1 apple cost Rs 10

10 apples will be bought at 10*1 = 10      Rs10.

Presuming the 10 apples are sold at Rs11.

Gain = Rs11 - Rs10 = Rs1

Gain% =   (1/10)*100% = 10%

Gain % = 10%

Hope this helps.