What is the unit digit in 7 pow 105

To find the unit digit lets break this in a manner that we get Unit digit to multiples 1,5,6 because that would fetch us same unit digits always

we know that 7 pow 4 = 51

So we can rewrite expression as

= (7 pow 4) pow 26 * 7
= 1 pow 26 * 7 (since 7 pow 4 gives unit digit 1)
= 7

Hence our unit digit will be 7