for fun :)

read expression

result_l1=$( bc <<< "scale=4; ( $expression )" )
result_l2=${result_l1::-2}$((${result_l1: -2:2}+5))

echo ${result_l2::-1}

read -p "Enter expression: " expr result=expr" | bc -l) printf "%.3f\n" "$result"

read -r exp

awk "BEGIN { printf \"%.3f\n\", $exp }"

• BEGIN keyword tells AWK to execute the code without any inputs files or stdin
• Does a shell expansion of $exp and evaluates the expression to 3 d.p.
• On a side note the backslash after printf is to escape the double quotes so that awk can treat that as a literal double quote.

read -r expression

evaluation={expression}" | bc)

printf '%.*f\n' 3 "$evaluation"