They've deleted part of each number in the answer choices, and although it is possible (but painful) to figure out what digits are missing, it's not necessary. In fact, all we need is the last digit.
It's useful to know that any number, when multiplied by itself over and over and over, will form a pattern with the units digits of each successive term. For example, here are the first 8 powers of 2:
2
4
8
16
32
64
128
256
etc
Notice that the last digits form a pattern: 2, 4, 8, 6... etc. So, if we plug n into 3*2^(n1), we get 3*2^24. Let's figure out what the units digit of 2^24 is. Since we know that every 4th term ends in 6, and we know that 2 to the 24th power will go through exactly 6 cycles of the pattern, and will therefore end with a 6. Only one of the answers ends in 6, but that's a trap.
We still need to deal with that 3. Any number you can think of that ends in 6, if multiplied by 3, will produce a number that ends in 8. Try it! So, since 2^24 ends in a 6, if we multiply it by 3, then the resulting huge number, even with a bunch of digits missing, must end in 8. Thus the answer is E.
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