floating point arithmetic operation error

Shell Programming and Scripting
1

I am writing a script in zsh shell, it fetchs a number from a file using the awk command, store it as a variable, which in my case is a small number 0.62000. I want to change this number by multiplying it by 1000 to become 620.0 using the command in the script

var2=$((var1*1000))

trouble is when the script is run it returns the error message

0.62000: syntax error: invalid arithmetic operator (error taken is ".62000")

I have also tried the following variations, but none of them works

var2=$var11000
var2=$var11000 | dc

Could someone tell me what is wrong?

Thanks

2 
var=.6211
newvar=$( echo "$var * 3.11" | bc -l )
echo $newvar
3

Thanks it works!

I tried to specify only one decimal space with the comand

newvar=$( echo "scale=1; $var * 1000" | bc -l )

but it doesn't seem to work, do you know why?

Thanks