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4__2__8=20

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2 Answers

Hi, Nicolette.

Rather than giving you the answer, I am going to give you two hints, and see if you can figure it out.

First, 20 is bigger than 4,2, and 8 added together, so there is going to be some multiplication involved.

Second, remember the order of operations: Parentheses, Exponents, Multiplication and Division, then Addition and Subtraction. For example: 12 - 2 x 5 = 2 because you have to do the multiplication before the subtraction.

Hope this helps!

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You nailed it Kathye!

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Nicolette,

Assuming all operators are acceptable including powers, one such possibility is:

42 -22 +8 = 20

16-4+8 = 20

This assumes that powers can be added. I can find no way to 20 with just those operators you have listed.

Arthur

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When powers are allowed, typically, you use the already given numbers in the problem as exponents.

For example valid use of powers would include 42_8, 4_28, the power tower 428 and, if parentheses are allowed, (42)8 where _ would be filled in with one of +,-,x,÷.

In this case, none of these three cases work, especially the power tower:

428 = 13407807929942597099574024998205846127479365820592393377723561443721764030073546976801874298166903427690031858186486050853753882811946569946433649006084096

Arthur...  there is a very simple answer using just those operators, as long as you honor the order of operations (which you should).

Roman...   LIKE.  :)

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