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Solve this question: Can you make 100 by interspersing any number of pluses and minuses within the string of digits 9 8 7 6 5 4 3 2 1? You can’t change the order of the digits! So what’s the least number of pluses and minuses needed to make 100? For instance, 98 - 7 - 6 + 54 - 32 shows one way of interspersing pluses and minuses, but since it equals 107, it’s not a solution.

Respuesta :

Answer:

98-76+54+3+21=100

  • 1 Plus
  • 3 Minuses

Step-by-step explanation:

Possible Variants are:

[tex]98 - 76 + 54 + 3 + 21 = 100\\9 - 8 + 76 + 54 - 32 + 1 = 100\\98 + 7 + 6 - 5 - 4 - 3 + 2 - 1 = 100\\98 - 7 - 6 - 5 - 4 + 3 + 21 = 100\\9 - 8 + 76 - 5 + 4 + 3 + 21 = 100\\98 - 7 + 6 + 5 + 4 - 3 - 2 - 1 = 100\\98 + 7 - 6 + 5 - 4 + 3 - 2 - 1 = 100[/tex]

[tex]98 + 7 - 6 + 5 - 4 - 3 + 2 + 1 = 100\\98 - 7 + 6 + 5 - 4 + 3 - 2 + 1 = 100\\98 - 7 + 6 - 5 + 4 + 3 + 2 - 1 = 100\\98 + 7 - 6 - 5 + 4 + 3 - 2 + 1 = 100\\98 - 7 - 6 + 5 + 4 + 3 + 2 + 1 = 100\\9 + 8 + 76 + 5 + 4 - 3 + 2 - 1 = 100\\9 + 8 + 76 + 5 - 4 + 3 + 2 + 1 = 100\\9 - 8 + 7 + 65 - 4 + 32 - 1 = 100\\[/tex]

From:

98-76+54+3+21=100

The least number of plus and minuses needed to make 100 are 1 and 3 respectively.

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