Math Puzzle

[ana]

hello friends!

i have a Question!

We have 5 number :4 - 5 - 7 - 8-11 and four operations - Subtraction - Multiplication - Split-plus (+ . - . * . / )

 

Between the 5 to number only want to use one of the four main action and the sum of our end is 20

for example:

8/4=2
2*11=22
22-7=15
15+5=20

and:

7*11=77

77 + 8 = 85

85 - 5 = 80
80/4=20

 

this Question have 24 answer!

[DejMar]

There are more than 24 arrangements of the operands and operators ...

Spoiler

Of the following list, the examples given in the problem are #14 and #10, respectively:
 1. { 5,  8,  7, 11,  4}; {+, *, -, /}
 2. { 5, 11,  4,  7,  8}; {+, /, *, -}
 3. { 5, 11,  7,  4,  8}; {+, *, /, -}
 4. { 5, 11,  7,  4,  8}; {*, -, /, +}
 5. { 7,  4,  8,  5, 11}; {/, *, -, +}
 6. { 7,  4,  8, 11,  5}; {/, *, +, -}
 7. { 7,  8,  4,  5, 11}; {*, /, -, +}
 8. { 7,  8,  4, 11,  5}; {*, /, +, -}
 9. { 7, 11,  5,  8,  4}; {*, -, +, /}
10. { 7, 11,  8,  5,  4}; {*, +, -, /}
11. { 8,  4,  7,  5, 11}; {/, *, -, +}
12. { 8,  4,  7, 11,  5}; {/, *, +, -}
13. { 8,  4, 11,  5,  7}; {/, *, +, -}
14. { 8,  4, 11,  7,  5}; {/, *, -, +}
15. { 8,  5,  7, 11,  4}; {+, *, -, /}
16. { 8,  7,  4,  5, 11}; {*, /, -, +}
17. { 8,  7,  4, 11,  5}; {*, /, +, -}
18. { 8, 11,  4,  5,  7}; {*, /, +, -}
19. { 8, 11,  4,  7,  5}; {*, /, -, +}
20. {11,  4,  8,  5,  7}; {/, *, +, -}
21. {11,  4,  8,  7,  5}; {/, *, -, +}
22. {11,  5,  4,  7,  8}; {+, /, *, -}
23. {11,  5,  7,  4,  8}; {+, *, /, -}
24. {11,  5,  7,  4,  8}; {*, -, /, +}
25. {11,  7,  5,  8,  4}; {*, -, +, /}
26. {11,  7,  8,  5,  4}; {*, +, -, /}
27. {11,  8,  4,  5,  7}; {*, /, +, -}
28. {11,  8,  4,  7,  5}; {*, /, -, +}

 

[Brainy Binary]

2 samples are:

8/4=2
2x11=22
22+5=27
27-7=20

7x11=77
77-5=72
72+8=80
80/4=20