Acceptable Responses:

(9+4) x 2=26 or (9+4) x 2

This solution is acceptable. The operations within the parenthesis are performed first; 13x2=26. For this contest, the equals sign '=' and target number are not required for the solution to be acceptable, as long as the target number is recorded in the proper place on the contest solution sheet.

9 + 4 = 13 13 x 2 = 26

This solution series is acceptable. The operations need not be all in a single equation; so this series of equations is correct. The "=" sign is required.

2 * (9+4) = 26 or 2 x (9 + 4) = 26

These solutions are acceptable. Multiplication is indicated with either a star (*) or an x.

Acceptable solutions with division:

Target 11: 4/2 + 9 or

+ 9 or 4 ÷ 2 + 9

Target 18:

or 9 x 4 / 2

Unacceptable Responses:

9 + 4 x 2 = 26

This solution is incorrect. By order of operations, multiplication is performed first. Thus, 9+4x2=17, not 26.

9 + 4 = 13 x 2 = 26

This solution is incorrect. Though we know the answer is intended as 9+4=13;13 x 2=26, the solution is simply not mathematically correct since 9+4 does not equal 13 x 2.

4 x 2 = 8 8 + 9 = 17 17 + 9 = 26

This solution is incorrect because the number 9 is used twice. Each number may be used once and only once in the solution.

2 (9 + 4) = 26

This solution is not acceptable because the operation of multiplication is assumed and not written.

3^2 + 1= 10

3^2 + 1= 10 means 3 X 3 + 1= 10

This solution is not acceptable because 2 is not part of the calculation with basic operations, and the 3 is used twice.