set masseven  2.
set massodd 1.
set totmass 0.

set comx 0.
set comy 0.
for {set i 1} {$i<=10} {incr i} {
   for {set j 1} {$j<=10} {incr j} {
      set prodij [expr {$i*$j}]
      if {[expr {$prodij % 2}]==0} {
         puts "$i $j $prodij $masseven"
         set comx [expr {$comx+$masseven*double($i)}]
         set comy [expr {$comy+$masseven*double($j)}]
         set totmass [expr $totmass+$masseven]
      } else {
         puts "$i $j $prodij $massodd"
         set comx [expr {$comx+$massodd*double($i)}]
         set comy [expr {$comy+$massodd*double($j)}]
         set totmass [expr $totmass+$massodd]
      }
   }
}

puts "com: (x,y)=([expr {$comx/$totmass}], [expr {$comy/$totmass}])"