This is just a simple calculator dialog. You need a mouse to use it. It doesn't need a specific mIRC version as far as I can tell. It SHOULD be easy to use. Hope it helps whoever tries it!

dialog calcu {
  title "Calculator"
  size -1 -1 149 100
  option dbu
  edit , 1, 1 1 147 14, autohs, read
  button 1, 2, 86 16 20 20
  button 2, 3, 107 16 20 20
  button 3, 4, 128 16 20 20
  button 4, 5, 86 37 20 20
  button 5, 6, 107 37 20 20
  button 6, 7, 128 37 20 20
  button 7, 8, 86 58 20 20
  button 8, 9, 107 58 20 20
  button 9, 10, 128 58 20 20
  button 0, 11, 86 79 20 20
  button ., 12, 107 79 20 20
  button Clear, 13, 2 16 20 20
  button %, 14, 44 16 20 20
  button x^2, 15, 44 37 20 20
  button x^3, 16, 44 58 20 20
  button x^y, 17, 44 79 20 20
  button pi, 18, 65 16 20 20
  button /, 19, 23 79 20 20
  button *, 20, 23 58 20 20
  button +, 21, 23 16 20 20
  button -, 22, 23 37 20 20
  button =, 23, 65 37 20 20
  button Off, 24, 2 37 20 20
  button (, 25, 2 58 20 20
  button ), 26, 2 79 20 20
  button Copy, 27, 128 79 20 20
  button "Round", 28, 65 58 20 20
}

On *:Dialog:calcu:sclick:*: {
  if (%sol = Yes) { did -r calcu 1 | set %sol No }
  if ($did = 2) { did -a calcu 1 1 }
  if ($did = 3) { did -a calcu 1 2 }
  if ($did = 4) { did -a calcu 1 3 }
  if ($did = 5) { did -a calcu 1 4 }
  if ($did = 6) { did -a calcu 1 5 }
  if ($did = 7) { did -a calcu 1 6 }
  if ($did = 8) { did -a calcu 1 7 }
  if ($did = 9) { did -a calcu 1 8 }
  if ($did = 10) { did -a calcu 1 9 }
  if ($did = 11) { did -a calcu 1 0 }
  if ($did = 12) { did -a calcu 1 . }
  if ($did = 13) { did -r calcu 1 }
  if ($did = 14) { did -a calcu 1 % }
  if ($did = 15) { did -a calcu 1 ^2 }
  if ($did = 16) { did -a calcu 1 ^3 }
  if ($did = 17) { did -a calcu 1 ^ }
  if ($did = 18) { did -a calcu 1 3.14159265 }
  if ($did = 19) { did -a calcu 1 / }
  if ($did = 20) { did -a calcu 1 * }
  if ($did = 21) { did -a calcu 1 + }
  if ($did = 22) { did -a calcu 1 - }
  if ($did = 23) {
    if (%rnd = yes) { set %prob $did(1) | did -r calcu 1 | set %ans $ceil($calc(%prob)) | did -a calcu 1 %ans }
    if (%rnd != yes) { set %prob $did(1) | did -r calcu 1 | set %ans $calc(%prob) | did -a calcu 1 %ans }
    set %sol Yes
    set %rnd No
  }
  if ($did = 24) { did -r calcu 1 }
  if ($did = 25) { did -a calcu 1 ( }
  if ($did = 26) { did -a calcu 1 ) }
  if ($did = 27) { clipboard %prob = %ans }
  if ($did = 28) { set %rnd Yes }
}

menu nicklist,menu,status,query,channel {
  Calculator: calcu
}

alias calcu {
  dialog -mdia calcu calcu
}