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If k is a positive integer, then the units digit of 15^k is always 5 (15^1 = 15, 15^2 = 225, 15^3 = 3375, 15^4 = ----5, etc)BTGmoderatorDC wrote: ↑Fri Apr 03, 2020 5:24 pm\(What\ is\ the\ units\ digit\ of\ 15^9\ -\ 16^6?\)
(A) 1
(B) 3
(C) 5
(D) 7
(E) 9
OA E
Source: Veritas Prep
The units digit of 15^9 is equal to the units digit of 5^9. Recall that when 5 is raised to any positive integer power, the units digit of the number will always be 5. Similarly, when 16 (or, equivalently, 6) is raised to any positive integer power, the units digit of the number will always be 6.BTGmoderatorDC wrote: ↑Fri Apr 03, 2020 5:24 pm\(What\ is\ the\ units\ digit\ of\ 15^9\ -\ 16^6?\)
(A) 1
(B) 3
(C) 5
(D) 7
(E) 9
OA E
Source: Veritas Prep
