Adding two reals in shell

Hello,

I want to add two real numbers in a shell script. I've tried doing it in several ways, but none have produced a good result.

The only command that seems to work partially is the following:

addition='echo $var1 + $var2 | bc -l'

It displays the result with an error:

script.sh: line 40: 1.560: command not found 

Knowing that 1.560 is the expected result.

What do you think?

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