What is the remainder of R=3^19 when divided by 10? Choose the correct choice
A) 0
B) 1
C) 5
D) 7
E) 9
I looked for patterns:   ^2 - units digit 9   ^3 - units digit 7   ^4 - units digit 1   ^5 - units digit 3   hence, we can see that when raised to a power which is multiple of 4, the units digit is 1, and when to an even power not multiple of 4, the units digit is 9   and we can then see:   ^16 - units digit 1, or   ^18 - units digit 9   and ^19 - units digit 7   therefore, R=when divided by 10, the remainder must be 7.7
<result>D</result>
What is the remainder of R=3^19 when divided by 10?