set multiplier 1
set b 0
label .l -textvariable multiplier
frame .f
foreach i {-1 4 7 36} {
    button .f.b$b -text $i -command "updateMultiplier $i"
    pack .f.b$b -side left -fill x -expand y
    incr b
}
pack .l -fill x
pack .f -fill both -expand y
proc updateMultiplier {i} {
    global multiplier

    set multiplier [expr $multiplier * $i]
}