Multiple choice general knowledge

What is the last digit in the unit place of 3*13*23*33*...*333?

  1. 1

  2. 3

  3. 5

  4. 7

  5. 9
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

To find the unit digit of the product 3×13×23×33×...×333, we only need the unit digits: 3×3×3×3×...×3. There are 34 terms (from 3 to 333 in steps of 10). The pattern of 3^n unit digits repeats every 4: 3,9,7,1. Since 34 mod 4 = 2, the unit digit is the second in the pattern: 9. Therefore, option E is correct.

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