How many numbers greater than 600 can be formed with the digits 5,6,7,8 if no digit is used more than once.

5678   
5687   
5768                        multiplied by 4
5786     (for the numbers in the 6, 7 & 8 thousands)
5867   
5876   

Current total: 24 numbers

657
675
678
687
658
685

End Total: 30

First step is to get rid of the square root. remember that a square root is the same as raising to the (1/2) power. see below: multiply exponents per exponent rules to get: remember you subtract exponents from the denominator and add exponents in the numerator so: simplify further: so a is the correct choice. if you don't understand this google exponent rules and it will you understand. look at the image results.