A=3.5e30
B=4.345e40

sed 's/D/E/g' File | awk '{print $1, $6*'$A', 10^($9)*'$B', $13, $8}' > File2

3.168808781403E+02 29825999184755995994350665720659968 71343531834366140263241767594070376448 ... etc

sed 's/D/E/g' File | awk '{printf "%.12E %.12E %.12E %.12E %.12En", $1, $6*'$A', 10^($9)*'$B', $13,$8 }' > File2

echo 71343531834366140263241767594070376448 | awk '{printf "%E",$1}'

7.134353E+37

awk 'BEGIN { printf("%En", 71343531834366140263241767594070376448); }'
7.134353E+37

$ awk 'BEGIN { printf "%en", 282048204209482034890 }' /dev/null
2.820482e+20

awk -v awkVar1="$A" -v awkVar2="$B" ... '{use awkVar1 without $}' file