High School Make the number 21 using the numbers: 1, 5, 6, 7

[vikasj007]

Make the number 21 using the numbers:
1, 5, 6, 7

you can use:
addition, subtraction, multipliaction and division

I promise you it is straight forward maths and NO tricks... you can only use each number once and you can't use say 15 (the 1 and the 5 together) and you can't do like 5^6 or anything.

 

[Rogerio]

1*.5*6*7 ?

 

[joshm]

1*.5*6*7 ?

No TRICKS.

\frac{6}{1-\frac{5}{7}}

 

[Galileo]

\frac{6}{1-\frac{5}{7}}

Nice

 

[mattmns]

No TRICKS.

\frac{6}{1-\frac{5}{7}}

wow I was way off, I was not thinking about anything like that at all. good job.

 

[vikasj007]

good work joshm, especially for your first post.