Select the odd group of numbers. (NOTE: Operations should be performed on the whole numbers, without breaking down the numbers into its constituent digits. E.g.13 - Operations on 13 such as adding /subtracting /multiplying etc. to 13 can be performed. Breaking down 13 into 1 and 3 and then performing mathematical operations on 1 and 3 is not allowed)
Answer & explanation
Correct answer: option 1
The logic followed here is
Ist number - (Ist number)2 - ( Ist number2 - 5 )
(15-220-215) = 15 - (152 -5) - (152 -10) ODD
(10-100-95) = 10 - (10)2 - (102 -5)
(20-400-395) = 20 - (20)2 - (202 -5)
(25-625-620) = 25 - (25)2 - (252 -5)