diff --git a/rekenmachine/index.html b/rekenmachine/index.html
new file mode 100644
index 0000000..66a51de
--- /dev/null
+++ b/rekenmachine/index.html
@@ -0,0 +1,179 @@
+<!DOCTYPE html>
+<html lang="en">
+<head>
+<meta charset="UTF-8">
+<meta name="viewport" content="width=device-width, initial-scale=1.0">
+<title>Calculator</title>
+<style>
+* {margin:0;padding:0;box-sizing:border-box;}
+body {
+    font-family:'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
+    background: linear-gradient(135deg,#667eea 0%,#764ba2 100%);
+    display:flex;justify-content:center;align-items:center;
+    min-height:100vh;overflow:hidden;
+}
+.calculator {
+    background:#2d3748;border-radius:20px;padding:30px;
+    box-shadow:0 20px 60px rgba(0,0,0,0.5);width:400px;
+}
+.display {
+    background:#1a202c;border-radius:10px;padding:20px;margin-bottom:20px;
+    text-align:right;min-height:100px;display:flex;flex-direction:column;justify-content:flex-end;
+}
+.equation {color:#a0aec0;font-size:18px;min-height:25px;margin-bottom:10px;}
+.current {color:#fff;font-size:36px;font-weight:600;}
+.buttons {display:grid;grid-template-columns:repeat(4,1fr);gap:12px;}
+button {
+    padding:24px;font-size:20px;font-weight:600;border:none;border-radius:10px;
+    cursor:pointer;transition:all 0.2s;color:#fff;
+}
+button:hover {transform:translateY(-2px);box-shadow:0 4px 12px rgba(0,0,0,0.3);}
+button:active {transform:translateY(0);}
+.number {background:#4a5568;}
+.operator {background:#ed8936;}
+.clear {background:#e53e3e;grid-column:span 2;}
+.equals {background:#48bb78;grid-column:span 2;}
+.bsod {
+    display:none;position:fixed;top:0;left:0;width:100vw;height:100vh;
+    background:#0078d7;color:white;font-family:'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
+    z-index:9999;padding:60px;overflow:hidden;flex-direction:column;justify-content:center;
+}
+.bsod.show {display:flex;}
+.bsod-content {max-width:800px;}
+.sad-face {font-size:120px;margin-bottom:40px;}
+.bsod h1 {font-size:48px;font-weight:400;margin-bottom:30px;}
+.bsod p {font-size:20px;line-height:1.6;margin-bottom:20px;}
+.progress {margin:40px 0;font-size:18px;}
+.error-details {margin-top:40px;font-size:14px;opacity:0.8;}
+.restart-btn {
+    display:none;margin-top:30px;padding:15px 40px;font-size:18px;background:white;color:#0078d7;
+    border:none;cursor:pointer;border-radius:5px;font-weight:600;
+}
+.restart-btn.show {display:inline-block;}
+.restart-btn:hover {background:#f0f0f0;}
+</style>
+</head>
+<body>
+<div class="calculator">
+    <div class="display">
+        <div class="equation" id="equation"></div>
+        <div class="current" id="current">0</div>
+    </div>
+    <div class="buttons">
+        <button class="clear" onclick="clearCalculator()">C</button>
+        <button class="operator" onclick="appendOperator('/')">/</button>
+        <button class="operator" onclick="appendOperator('*')">×</button>
+
+        <button class="number" onclick="appendNumber('7')">7</button>
+        <button class="number" onclick="appendNumber('8')">8</button>
+        <button class="number" onclick="appendNumber('9')">9</button>
+        <button class="operator" onclick="appendOperator('-')">-</button>
+
+        <button class="number" onclick="appendNumber('4')">4</button>
+        <button class="number" onclick="appendNumber('5')">5</button>
+        <button class="number" onclick="appendNumber('6')">6</button>
+        <button class="operator" onclick="appendOperator('+')">+</button>
+
+        <button class="number" onclick="appendNumber('1')">1</button>
+        <button class="number" onclick="appendNumber('2')">2</button>
+        <button class="number" onclick="appendNumber('3')">3</button>
+        <button class="number" onclick="appendNumber('0')">0</button>
+
+        <button class="number" onclick="appendNumber('.')">.</button>
+        <button class="equals" onclick="triggerBSOD()">=</button>
+    </div>
+</div>
+
+<div class="bsod" id="bsod">
+    <div class="bsod-content">
+        <div class="sad-face">:(</div>
+        <h1>Your PC ran into a problem and needs to restart.</h1>
+        <p>We're just collecting some error info, and then we'll restart for you.</p>
+        <div class="progress"><span id="progress">0</span>% complete</div>
+        <div class="error-details">
+            <p>If you'd like to know more, you can search online later for this error: pech.</p>
+            <p>Stop code: 0x0000007B (0x00000034, 0xC0000034, 0x00000000, 0x00000000)</p>
+            <p>What failed: your calculates were so ass it crashed</p>
+        </div>
+        <button class="restart-btn" id="restartBtn" onclick="location.reload()">Restart</button>
+    </div>
+</div>
+
+<script>
+let currentValue='0', previousValue='', operation='', shouldResetScreen=false;
+
+function updateDisplay(){
+    document.getElementById('current').textContent=currentValue;
+    let equationText=previousValue;
+    if(operation) equationText+=' '+operation;
+    document.getElementById('equation').textContent=equationText;
+}
+
+function appendNumber(num){
+    if(currentValue==='0'||shouldResetScreen){currentValue=num; shouldResetScreen=false;}
+    else{currentValue+=num;}
+    updateDisplay();
+}
+
+function appendOperator(op){
+    if(operation&&!shouldResetScreen) calculate();
+    previousValue=currentValue;
+    operation=op;
+    shouldResetScreen=true;
+    updateDisplay();
+}
+
+function calculate(){
+    const prev=parseFloat(previousValue);
+    const current=parseFloat(currentValue);
+    if(isNaN(prev)||isNaN(current)) return;
+    let result;
+    switch(operation){
+        case'+':result=prev+current;break;
+        case'-':result=prev-current;break;
+        case'*':result=prev*current;break;
+        case'/':result=prev/current;break;
+        default:return;
+    }
+    currentValue=result.toString();
+    operation='';
+    previousValue='';
+    shouldResetScreen=true;
+    updateDisplay();
+}
+
+function clearCalculator(){currentValue='0'; previousValue=''; operation=''; shouldResetScreen=false; updateDisplay();}
+
+function triggerBSOD(){
+    // fullscreen request
+    if(document.documentElement.requestFullscreen) document.documentElement.requestFullscreen();
+    document.body.style.cursor='none';
+
+    const bsod=document.getElementById('bsod');
+    const progressElement=document.getElementById('progress');
+    const restartBtn=document.getElementById('restartBtn');
+
+    bsod.classList.add('show');
+
+    let progress=0;
+    const interval=setInterval(()=>{
+        progress+=Math.floor(Math.random()*8)+1;
+        if(progress>=100){progress=100; clearInterval(interval);
+            setTimeout(()=>{restartBtn.classList.add('show');},500);}
+        progressElement.textContent=progress;
+    },200);
+}
+
+// Keyboard support + Enter = BSOD
+document.addEventListener('keydown', e=>{
+    if(e.key>='0'&&e.key<='9') appendNumber(e.key);
+    else if(e.key=='.') appendNumber('.');
+    else if(e.key==='+'||e.key==='-'||e.key==='*'||e.key==='/') appendOperator(e.key);
+    else if(e.key==='Enter'||e.key==='='){e.preventDefault(); triggerBSOD();}
+    else if(e.key==='Escape'||e.key==='c'||e.key==='C') clearCalculator();
+});
+
+updateDisplay();
+</script>
+</body>
+</html>
