A simple mIRC calculator that only uses addition subtraction and multiplication. I will be adding square roots and many other things soon.
Edit: Major update! I'm currently working on the +/- key. (Positive and negative)

I will soon be adding Scientific View, so get ready people! (It might take like 5 days though)
Edit: Changed +/- key to (-) due to mIRC not being able to recognize - in an editbox for some reason..

menu * {
  -
  $iif(!$dialog(Calculator),Calculator,$style(2) Calculator): dialog -m Calculator Calculator
  -
}
Dialog Calculator {
  Title "Calculator"
  Size -1 -1 172 160
  Button "1", 1, 1 95 28 20, 
  Button "2", 2, 29 95 28 20, 
  Button "3", 3, 58 95 28 20, 
  Button "4", 4, 1 116 28 20, 
  Button "5", 5, 30 116 28 20, 
  Button "6", 6, 58 116 28 20, 
  Button "7", 7, 0 137 28 20, 
  Button "8", 8, 29 137 28 20, 
  Button "9", 9, 58 137 28 20, 
  Button "*", 10, 138 115 28 20, 
  Button "-", 11, 138 136 28 20, 
  Button "+", 12, 138 94 28 20, 
  edit "",  13, 0 1 140 25, read
  Button "Clear", 14, 87 136 50 20, 
  Button "Exit", 15, 87 115 50 20, Cancel, 
  Button "Ok", 16, 87 94 50 20, ok
  Button "Calculate", 17, 1 26 170 20
  Button "Sqrt", 18, 87 75 25 20
  Button ".", 19, 29 75 28 20
  Button "/", 20, 138 75 28 20
  Button "0", 21, 1 75 28 20
  Button "^", 22, 113 75 25 20
  Button "( - )", 23, 58 75 28 20
  Button "Pi", 24, 1 55 28 20
  Button "1/x", 25, 29 55 28 20
  Button "( )", 26, 58 55 28 20
  Button "MS", 27, 87 55 25 20
  Edit "", 28, 141 1 30 25, read
  Button "MR", 29, 113 55 25 20
  Button "MC", 30, 138 55 28 20
}
on *:DIALOG:Calculator:*:*: {
  if ($devent == sclick) {
    if ($did <= 9) {
      did -a Calculator 13 $did
    }
    if ($did == 10) {
      did -a Calculator 13 *
    }
    if ($did == 11) {
      did -a Calculator 13 -
    }
    if ($did == 12) {
      did -a Calculator 13 +
    }
    if ($did == 14) {
      did -r Calculator 13
    }
    if ($did == 17) {
      did -ra Calculator 13 $calc($did(13).text)
    } 
    if ($did == 18) {
      did -ra Calculator 13 $sqrt($did(13).text)
    }  
    if ($did == 19) {
      did -a Calculator 13 .
    } 
    if ($did == 20) {
      did -a Calculator 13 /   
    } 
    if ($did == 21) {
      did -a Calculator 13 0
    }  
    if ($did == 22) {
      did -a Calculator 13 ^
    }  
    if ($did == 23) {
      did -ra Calculator 13 $replace($did(13).text,$did(13).text,- $+ $did(13).text)
    }
    if ($did == 24) {
      did -a Calculator 13 3.14
    }  
    if ($did == 25) {
      did -ra Calculator 13 $calc(1 / $did(13).text)
    }
    if ($did == 26) {
      did -ra Calculator 13 ( $+ $did(13).text $+ )
    }  
    if ($did == 27) {
      did -ra Calculator 28 M
      set %calcmem $did(13).text
    }  
    if ($did == 29) {
      did -ra Calculator 13 %calcmem 
    }
    if ($did == 30) {
      did -r Calculator 28
      unset %calcmem
    }
  }
}