Finding the digit at unit place in the given product

Property 6 The units digit of the square of a natural number is the units digit of the square of the digit at units place of the given natural number.

What is the digit in unit's place of the product 51 xx 52 xx 53 ….59?

What is the digit at unit's place of 9^(n)?

Find the digit in the units place of (676)^99 .

In a three digit number, the digit in the units place is four times the digit in the hundred place. If the digits in the units place and the tens place are interchanged, the new number so formed is 1 more than the original number. If the digit in the hundred place is one third of the digit in the tens place, what is the original number?

In a three-digit number, the digit in the unit's place is four times the digit in the hundred's place. If the digit in the unit's place and the ten's place are inter changed, the new number so formed is 18 more than the original number. If the digit in the hundred's place is one-third of the digit in the ten's place, then what is 25% of the original number?