How do I convert Quinary numbers into decimals?

Answer 1

Quinary means base 5 so each place is a power of 5
Going from right to left add up the following:
The first digit
The second digit multiplied by 5
The third digit multiplied by 5^2 or 25
The fourth digit multiplied by 5^3 or 125
The fifth digit multiplied by 5^4 or 625
and so on

for example if your base 5 number is 3142 then
2 + 5x4 + 25x1 + 125x3

Answer 2

Here's a good explanation of base 5 (quinary) numbers.
http://mathforum.org/library/drmath/view/55750.html

Answer 3

You could multiply and add or easier take the log base 5 multiply by 0.699 and take the antilog base 10. That would hurt less.