I see the pattern when the numbers are raised to a small integer, but once at a^8 I am lost....Can someone please help me with the following....

a=28 28^749(mod1174)

a^1 = 28(mod1147)

a^2 = 784 (mod1147)

a^4 = 1011 (mod1147)

I see how 1011 came by...28^4=614656/1147=535

then 614656-535*1147=1011

However, for the following

a^8 = {I know its 144 from the book but how did that come about?}

if I take 28^8 its to large to really work with the actual interger..