Convert output of linux 'time' command to show seconds only

After executing Linux 'time' command, the following output is obtained:
real 2m52.293s
user 1m39.670s
sys 0m4.370s

Use the following command to extract value for 'real' time only and convert the output to seconds only (i.e., convert 2m52.293s into 172.293):
cat outputFile* | grep real | cut -f 2 | sed 's/m/*60+/' | sed 's/s//g' | bc