Find the remainder when 7 to the power of 103 is divided by 25

What is the remainder of 7¹⁰³

7103 
= 7102(7)
= 7(49)51
= 7(50-1)51
= 7(5051 - 51(50)50+(51)(25)(50)49 ... + (51)(50) - 1)
= 7(50k - 1)
= 350k - 7
= 350k + 25 - 25 - 7
= (350k - 25) + 25 -7
= (350k-25)+18 ...(a)

When 'a' is divided by 25 it leaves a remainder 18. Hence, when 7103 is divided by 25,it leaves a remainder 18.

Source: toppr.com