Multiple choice

220 - x is divisible by 5. If x is an integer, which of the following is a possible value of x?

  1. 0

  2. 1

  3. 6

  4. 1 or 6
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

21 = 2, 22 = 4, 23 = 8, 24 = 16, 25 = 32, 26 = 64… We can find out that the units digit of 2n is the same as the units digit of 2(n + 4). So, the units digit of 220 would be the same as the units digit of 24, which is 6. If the units digit of 2(20) - x is 0 or 5, then it can be divisible by 5. So, x should be 1 or 6.

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