matt: ~ $ ./i.sh 
./i.sh: line 5: let: upSeconds=22676.85 78157.21 && echo ): syntax error: invalid arithmetic operator (error token is ".85 78157.21 && echo )")
./i.sh: line 6: %60: syntax error: operand expected (error token is "%60")
./i.sh: line 7: /60%60: syntax error: operand expected (error token is "/60%60")
./i.sh: line 8: /3600%24: syntax error: operand expected (error token is "/3600%24")
./i.sh: line 9: /86400: syntax error: operand expected (error token is "/86400")
./i.sh: line 10: [: : integer expression expected