Multiple choice

Find the sum of all three-digit natural numbers, which on being divided by 5, leave a remainder equal to 4.

  1. 57,270

  2. 96,780

  3. 49,880

  4. 99,270
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D Correct answer
AI explanation

The three-digit numbers leaving a remainder of 4 when divided by 5 form an arithmetic progression starting at 104 and ending at 999, with a common difference of 5. Calculate the number of terms using n equals the difference of the first and last terms divided by the common difference plus 1, giving 999 minus 104 divided by 5 plus 1, which equals 180. Apply the arithmetic series sum formula: S equals n multiplied by the sum of the first and last terms divided by 2. The sum is 180 multiplied by 104 plus 999 divided by 2, resulting in 180 multiplied by 551.5, which equals 99270.

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