The integers 1-40 are written on a blackboard. The following operation is then repeated 39 times. In each repetition, any pair of numbers (say a and b) are erased and a new number (a + b – 1) is written in its place. What will be the number left on the board at the end?

820

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1601

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781

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859

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Solution

The correct option is C 781
Option C is the correct answer. Check the video for the approach.

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The integers 1-40 are written on a blackboard. The following operation is then repeated 39 times. In each repetition, any pair of numbers (say a and b) are erased and a new number (a + b – 1) is written in its place. What will be the number left on the board at the end?

The correct option is C 781Option C is the correct answer. Check the video for the approach.

The correct option is C 781
Option C is the correct answer. Check the video for the approach.