Suppose x is raised to the power y and we need to find unit digit of x^ySo, we will first divide y by 4 and find the remainder thus obtained. Since on dividing and integral number by four can yield only four remainders --> 0, 1, 2 and 3.This method applies for 4 values of x only, because for other values, you can split the values in the 4 values of x:-x = 2, 3, 7 and 8.For 2====If remainder [y/4] is 1,unit digit of = 2If remainder is 2, unit digit of = 4If remainder is 3,unit digit of = 8If remainder is 0,unit digit of = 6

For 3====If remainder is 1,unit digit of = 3If remainder is 2,unit digit of = 9If remainder is 3,unit digit of = 7If remainder is 0,unit digit of = 1

For 7====If remainder is 1,unit digit of = 7If remainder is 2,unit digit of = 9If remainder is 3,unit digit of = 3If remainder is 0,unit digit of = 1

For 8====If remainder is 1,unit digit of = 8If remainder is 2,unit digit of = 4If remainder is 3,unit digit of = 2If remainder is 4,unit digit of = 6

For memorising that of 3 and 7, you can check the unit digit of when 3 and 7 are raised to the power remainder [power = remainder]. For 2 and 8 this trend doesn't works.So in your question,

Dividing 333 by 4, we get remainder 1.So using table, when remainder is 3, unit digit of 3 [because the unit digit of 373 raised to power something is because of its originalunit digit only] will be 3.Hence unit digit of will be 3.