Problem Solving (PS) | Re: What is the remainder when 2^20 is divided by 10 ?

Hi,

TWO ways-

1) Cyclic pattern of units digit-
Remainder when div by 10 is nothing BUT unitsdigit
\(2^1 = 2.........
2^2 = 4..........
2^3 = 8..........
2^4 = 16.. or... 6........\)
and this carries on in same pattern.... 2, 4, 8, 6, 2, 4, 8, 6... so 20 is div by 4..
so 2^20 will have UNITS digit same as 4th power..
ans 6

2) binomial expansion\(2^{20} = (2^5)^4 = 32^4 = (30+2)^4\) ..
Now the above
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