Correct Answer - Option 4 : 8
Given
(917)753 + (23)512
Concept
To find the unit digit of the number, cyclicity method is used.
Cyclicity of 7 is 4 i.e 7 = 7, 7 = 49, 7 = 343,7 = 2401, 7 = 7207 after 4 unit digit is start to repeat so, cyclicity of 7 is 4
Cyclicity of 3 is also 4 i.e. 3 = 3, 3 = 9, 3 = 27, 3 = 81, 3 = 243 after 4..repeation starts. So, cyclicity is 4
Calculation
(917)753
When 753 is divided by 4, remainder is 1.So, (7) = 7
(23)512
When 512 is divided by 4, remainder is 0.So, (3) = 1
So, unit digit = 7 + 1
⇒ 8
∴ Unit digit is 8