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diff --git a/Recruit-Training/Advanced-Recruit-Training/Telemetry-Teaser/src/App.tsx b/Recruit-Training/Advanced-Recruit-Training/Telemetry-Teaser/src/App.tsx
index 488bc934..2ce4cc2b 100644
--- a/Recruit-Training/Advanced-Recruit-Training/Telemetry-Teaser/src/App.tsx
+++ b/Recruit-Training/Advanced-Recruit-Training/Telemetry-Teaser/src/App.tsx
@@ -1,12 +1,240 @@
+import React, {
+  useCallback,
+  useMemo,
+  useReducer,
+  useRef,
+  useState,
+} from "react";
+
 import BatteryInput from "~/components/batteryInput";
 import Header from "~/components/header";
 import SpeedInput from "~/components/speedInput";
 import WeatherInput from "~/components/weatherInput";
 
-const App = () => {
-  const calculateRange = () => {
-    return;
+// 1. Define the State interface
+interface State {
+  speed: number | string;
+  battery: number | string;
+  weather: number | string;
+  changed: {
+    speed: boolean;
+    battery: boolean;
+    weather: boolean;
+  };
+}
+
+type ActionType =
+  | {
+      type: "UPDATE_SPEED_AND_CHANGED"; // New combined action type
+      payload: {
+        speed: number | string; // Speed value
+        altered: boolean; // Indicates if the input was changed
+      };
+    }
+  | {
+      type: "UPDATE_BATTERY_AND_CHANGED"; // New combined action type
+      payload: {
+        battery: number | string; // battery value
+        altered: boolean; // Indicates if the input was changed
+      };
+    }
+  | {
+      type: "UPDATE_WEATHER_AND_CHANGED"; // New combined action type
+      payload: {
+        weather: number | string; // battery value
+        altered: boolean; // Indicates if the input was changed
+      };
+    };
+
+const initialState: State = {
+  speed: "",
+  battery: "",
+  weather: 0,
+  changed: {
+    speed: false,
+    battery: false,
+    weather: false,
+  },
+};
+
+const reducer = (state: State, action: ActionType): State => {
+  switch (action.type) {
+    case "UPDATE_SPEED_AND_CHANGED":
+      return {
+        ...state,
+        speed: action.payload.speed,
+        changed: {
+          ...state.changed,
+          speed: action.payload.altered,
+        },
+      };
+    case "UPDATE_BATTERY_AND_CHANGED":
+      return {
+        ...state,
+        battery: action.payload.battery,
+        changed: {
+          ...state.changed,
+          battery: action.payload.altered,
+        },
+      };
+    case "UPDATE_WEATHER_AND_CHANGED":
+      return {
+        ...state,
+        weather: action.payload.weather,
+        changed: {
+          ...state.changed,
+          weather: action.payload.altered,
+        },
+      };
+    default:
+      return state;
   }
+};
+const App = () => {
+  const [displayRange, setSD] = useState(false);
+  const [state, dispatch] = useReducer(reducer, initialState);
+  const { speed, battery, weather } = state; //initialize the state
+
+  //to avoid the type errors:
+  const handleSpeedChange = useCallback(
+    (e: React.ChangeEvent<HTMLInputElement>) => {
+      const value = e.target.value;
+      dispatch({
+        type: "UPDATE_SPEED_AND_CHANGED",
+        payload: {
+          speed: value === "" ? "" : Number(value), //empty input is allowed or the input is converted to a number
+          altered: true, //the input changed so we chnage it to true
+        },
+      });
+      setSD(false);
+      console.log("Speed:", value); // Add this line
+    },
+    [],
+  );
+
+  const handleBatteryChange = useCallback(
+    (e: React.ChangeEvent<HTMLInputElement>) => {
+      const value = e.target.value;
+      dispatch({
+        type: "UPDATE_BATTERY_AND_CHANGED",
+        payload: {
+          battery: value === "" ? "" : Number(value), //empty input is allowed or the input is converted to a number
+          altered: true, //the input changed so we chnage it to true
+        },
+      });
+      setSD(false);
+    },
+    [],
+  );
+
+  const handleWeatherChange = useCallback(
+    (e: React.ChangeEvent<HTMLInputElement>) => {
+      const value = e.target.value;
+      // Allow empty input, or convert to a number
+      dispatch({
+        type: "UPDATE_WEATHER_AND_CHANGED",
+        payload: {
+          weather: value === "" ? "" : Number(value), //empty input is allowed or the input is converted to a number
+          altered: true, //the input changed so we chnage it to true
+        },
+      });
+      setSD(false);
+    },
+    [],
+  );
+
+  const validInputs = useMemo(() => {
+    //reset battery and speed
+    let speedError = "";
+    let batteryError = "";
+    let isValid = true;
+
+    //check the changed fields
+    if (state.changed.speed) {
+      if (state.speed === "") {
+        isValid = false;
+        speedError = "Speed is required";
+      } else if (Number(state.speed) < 0 || Number(state.speed) > 90) {
+        isValid = false;
+        speedError = "The speed should be within the range of 0 to 90";
+      }
+    } else if (state.speed === "") {
+      //when nothing has been entered yet
+      isValid = false;
+    }
+
+    if (state.changed.battery) {
+      if (state.battery === "") {
+        isValid = false;
+        batteryError = "Battery is required";
+      } else if (
+        typeof state.battery === "number" &&
+        (state.battery < 0 || state.battery > 100)
+      ) {
+        isValid = false;
+        batteryError =
+          "The battery percentage should be within the range of 0 to 100";
+      }
+    } else if (state.battery === "") {
+      //when nothing has been entered yet
+      isValid = false;
+    }
+
+    return { speedError, batteryError, isValid };
+  }, [state.changed, state.speed, state.battery]); //recompute the answer if speed or battery change
+
+  /*const calculateRange = useMemo(() => {
+    const { speedError, batteryError, isValid } = validInputs;
+
+    if (!isValid) {
+      console.error(speedError, batteryError);
+      return null;
+    }
+    return (
+      -(
+        (Number(state.speed) * Number(state.speed) * Number(state.battery)) /
+        2500
+      ) +
+      4 * Number(state.battery) +
+      Number(state.weather)
+    );
+  }, [validInputs.isValid, state.battery, state.speed, state.weather]);
+
+  const handleClick = () => {
+    const range = calculateRange; // Get the calculated range
+    rangeRef.current = range; // Set the calculated range to the ref
+    console.log(rangeRef.current);
+    console.log(typeof rangeRef.current);
+    console.log(rangeRef.current !== null);
+  };*/
+
+  const calculatedRange = useMemo(() => {
+    const { isValid } = validInputs;
+    if (isValid)
+      return (
+        -(
+          (Number(state.speed) * Number(state.speed) * Number(state.battery)) /
+          2500
+        ) +
+        4 * Number(state.battery) +
+        Number(state.weather)
+      );
+    return null;
+  }, [
+    validInputs.isValid,
+    state.speed,
+    state.battery,
+    state.weather,
+    displayRange,
+  ]);
+
+  const handleClick = () => {
+    if (validInputs.isValid) {
+      setSD(true); // Show the range if inputs are valid
+    } else {
+      setSD(false); // Hide or show an error message if inputs are invalid
+    }
+  };
 
   return (
     <div className="h-screen w-screen bg-[#212121]">
@@ -14,11 +242,42 @@ const App = () => {
         <Header />
         <form name="simulator" className="flex w-full flex-col items-center">
           <div className="mb-4 flex w-full flex-col items-center gap-y-4">
-            <SpeedInput />
-            <BatteryInput />
+            <SpeedInput value={speed} onChange={handleSpeedChange} />
+            {validInputs.speedError && (
+              <div className="text-red-500">{validInputs.speedError}</div>
+            )}
+            {/* speed error message */}
+            <BatteryInput value={battery} onChange={handleBatteryChange} />
+            {validInputs.batteryError && (
+              <div className="text-red-500">{validInputs.batteryError}</div>
+            )}
+            {/* Battery error message */}
           </div>
           <div className="flex w-full flex-row justify-center gap-4">
-            <WeatherInput />
+            <WeatherInput value={weather} onChange={handleWeatherChange} />
+          </div>
+
+          {/*make the button*/}
+          <div className="mt-8 text-center">
+            {" "}
+            {/* Add text-center here */}
+            <button
+              type="button"
+              onClick={handleClick}
+              className="w-48 rounded bg-blue-500 px-4 py-2 font-bold text-white"
+            >
+              Calculate
+            </button>
+            <div id="range-output" className="mt-4">
+              {displayRange && calculatedRange !== null ? (
+                <p>
+                  The predicted range of the Eylsia is{" "}
+                  {calculatedRange.toFixed(2)} km.
+                </p>
+              ) : (
+                <p></p>
+              )}
+            </div>
           </div>
         </form>
       </div>
diff --git a/Recruit-Training/Advanced-Recruit-Training/Telemetry-Teaser/src/InputProps.ts b/Recruit-Training/Advanced-Recruit-Training/Telemetry-Teaser/src/InputProps.ts
new file mode 100644
index 00000000..f96d23da
--- /dev/null
+++ b/Recruit-Training/Advanced-Recruit-Training/Telemetry-Teaser/src/InputProps.ts
@@ -0,0 +1,5 @@
+// Define the props type
+export interface InputProps {
+  value: number | string; // Expecting a string for the input value
+  onChange: (e: React.ChangeEvent<HTMLInputElement>) => void; // Function to handle changes
+}
diff --git a/Recruit-Training/Advanced-Recruit-Training/Telemetry-Teaser/src/components/batteryInput/index.tsx b/Recruit-Training/Advanced-Recruit-Training/Telemetry-Teaser/src/components/batteryInput/index.tsx
index ca4586c0..d08ae47c 100644
--- a/Recruit-Training/Advanced-Recruit-Training/Telemetry-Teaser/src/components/batteryInput/index.tsx
+++ b/Recruit-Training/Advanced-Recruit-Training/Telemetry-Teaser/src/components/batteryInput/index.tsx
@@ -1,4 +1,6 @@
-const BatteryInput = () => {
+import type { InputProps } from "~/InputProps";
+
+const BatteryInput: React.FC<InputProps> = ({ value, onChange }) => {
   return (
     <div className="flex w-full flex-col items-center gap-2">
       <label>Battery Percentage (%):</label>
@@ -8,6 +10,9 @@ const BatteryInput = () => {
         name="battery"
         type="number"
         placeholder="Battery"
+        value={value}
+        onChange={onChange}
+        required
       />
     </div>
   );
diff --git a/Recruit-Training/Advanced-Recruit-Training/Telemetry-Teaser/src/components/speedInput/index.tsx b/Recruit-Training/Advanced-Recruit-Training/Telemetry-Teaser/src/components/speedInput/index.tsx
index aa381c14..3e7f825c 100644
--- a/Recruit-Training/Advanced-Recruit-Training/Telemetry-Teaser/src/components/speedInput/index.tsx
+++ b/Recruit-Training/Advanced-Recruit-Training/Telemetry-Teaser/src/components/speedInput/index.tsx
@@ -1,4 +1,6 @@
-const SpeedInput = () => {
+import type { InputProps } from "~/InputProps";
+
+const SpeedInput: React.FC<InputProps> = ({ value, onChange }) => {
   return (
     <>
       <div className="flex w-full flex-col items-center gap-2">
@@ -9,6 +11,9 @@ const SpeedInput = () => {
           name="speed"
           type="number"
           placeholder="Speed"
+          value={value}
+          onChange={onChange}
+          required
         />
       </div>
     </>
diff --git a/Recruit-Training/Advanced-Recruit-Training/Telemetry-Teaser/src/components/weatherInput/index.tsx b/Recruit-Training/Advanced-Recruit-Training/Telemetry-Teaser/src/components/weatherInput/index.tsx
index fd5ad35b..e913006c 100644
--- a/Recruit-Training/Advanced-Recruit-Training/Telemetry-Teaser/src/components/weatherInput/index.tsx
+++ b/Recruit-Training/Advanced-Recruit-Training/Telemetry-Teaser/src/components/weatherInput/index.tsx
@@ -1,4 +1,8 @@
-const WeatherInput = () => {
+import React from "react";
+
+import type { InputProps } from "~/InputProps";
+
+const WeatherInput: React.FC<InputProps> = ({ value, onChange }) => {
   return (
     <>
       <img src="/Cloud.png" height="66px" width="66px" alt="Cloud" />
@@ -8,7 +12,8 @@ const WeatherInput = () => {
         type="range"
         min="0"
         max="100"
-        value="50"
+        value={value}
+        onChange={onChange}
       />
       <img src="/Sun.png" height="66px" width="66px" alt="Sun" />
     </>