Find the digit.

Is it = 6

it shud be 6...
(5!+9)(6!+4) has 6 in its units place since 5! and 6! end in zeroes and 9 x 4 = 36
and we know 6 to the power any positive integer we get 6 only in the units digit....

sigma for dese type of sums...
u shud know de cyclicity of digits....
for example 2...
2¹=2
2²=4
2³=8
2⁴-16
2⁵=32

we see that the units digit repeat in the pattern 2,4,6,8,2,4,6,8 with a period of 4...
all digits have dis cyclicity
cyclicity of 3 is 4(3,9,7,1)
cyclicity of 4 is 2(4,6)
cyclicity of 5 is 1(only 5)
and so on.....

well every such number has to have a cycle of the last digits.
the cycle can be of max period 4.
this is for the last digit only.
for the tens digit and all, the cycle has a larger period, though their are numbers with small periods of their tens digits too like 7...
it is so cause n^5 - n is always divisible by 10 ...