The units digits of 3^1, 3^2, 3^3, 3^4, 3^5, ldots are 3, 9, 7, 1, 3, ldots The units digit of 3^20 is:

  1. 9
  2. 1
  3. 7
  4. 3
Answer

B) 1

The pattern repeats every 4 powers; 20 is a multiple of 4, so the units digit is the 4th one, 1. SLO M-09-A-10 · Understanding

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