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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!


You nailed it Kathye!


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.



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.  :)