Please help with simple grade 7 question?

The numbers from 1 to 10 are written 10 times each on a board. Now the children play the following game: One child deletes two numbers off the board and writes instead the sum of the two numbers minus 1. Then, a second child does the same, and so on until there is only one number left on the board. The last number is

A) less than 11

B) 11

C) 46

D) greater than 46

E) depends on the course of the game

2 Answers

  • 7 years ago
    Best Answer

    There are 100 numbers on the board.

    Therefore there are 99 sums to be made, before 1 final answer is written on the board. (Every sum takes two numbers and adds 1. If there is one left, after 99 sums, you can not m ake another sum.)

    So the end of the game has the sum of all the numbers on the starting board, minus 99 (you do minus 1 99 times).

    The final number will be 550-99=451. So it's D.

    (Are you sure you wrote the question down correctly? Since the answer is so much higher than the possibilities.)

  • AskJoe
    Lv 7
    7 years ago


Still have questions? Get your answers by asking now.