<ol>
<li>If the nth term of a sequence is given by the expression 2*4^(n-1), what is the value of the units digit of the 131st term in the sequence?</li>
</ol>
<p>A 0
B 2
C 3
D 6
E 8</p>
<p>Please explain how you get the answer. Thanks in advance!</p>
<h2>I get a long decimal number after calculation, with x10^78 attached. Now how do I find out its unit digit :(</h2>
<p>section 3 (math) Princeton Review 3
Practice Test 1</p>
<p>2* 4^130 = 2* 2^260
2^261…
2^1- unit digit 2
2^2…unit digit 4
2^3 - Unit digit 8
2^4- unit digit 6
observe the following pattern
260/4=65 0 remainder…( or 4 reminder)
therefore, ans. must be 6…</p>
<p>wow, thanks! I got what you did and learnt the logic. The answer is 2
your method is good! … just that we are in the search for the unit digit of 2^261 (not 260), so it would be indeed 2
thanks once again. you solved my problem.</p>