diff --git a/assignments/solutions_3.md b/assignments/solutions_3.md
new file mode 100644
index 0000000..63cf698
--- /dev/null
+++ b/assignments/solutions_3.md
@@ -0,0 +1,34 @@
+fn main() {
+   subtract();
+   multiply();
+   divide(); 
+}
+
+fn subtract() -> u16{
+    let  a = 10_u16;
+    let  b = 20_u16;
+
+   let subt = a - b;
+    println!("The answer is: {}" sub);
+
+    sub
+}
+
+fn multiply() -> u32 {
+    let (a, b): (u32, u32) = (13, 10);
+
+    let mult = a * b;
+    println!("The product is: {}", mult);
+
+    mult;
+}
+
+fn divide() -> u8{
+    let  a: u8 = 14;
+    let  b: u8 = 2;
+
+    let div = a / b;
+    println!("The answer is: {}" div);
+
+    div;
+}
\ No newline at end of file
diff --git a/src/errors.cairo b/src/errors.cairo
index 524d2ad..a3e441c 100644
--- a/src/errors.cairo
+++ b/src/errors.cairo
@@ -4,4 +4,5 @@ pub mod Errors {
     pub const ZERO_ADDRESS: felt252 = 'ZERO ADDRESS!';
     pub const SAME_ADDRESS: felt252 = 'CANNOT BE SAME ADDRESS!';
     pub const ZERO_VALUE: felt252 = 'CANNOT BE ZERO_VALUE!';
+    pub const EMPTY_STRING: felt252 = 'CANNOT BE EMPTY STRING!';
 }
diff --git a/src/intro_to_bytearray.cairo b/src/intro_to_bytearray.cairo
new file mode 100644
index 0000000..7b53a29
--- /dev/null
+++ b/src/intro_to_bytearray.cairo
@@ -0,0 +1,7 @@
+// for any string exceeding 31 chars, use ByteArray
+pub fn run() -> ByteArray {
+    let name_of_school: ByteArray = "Cairo Bootcamp 3 2024 in Kaduna is holding as a hybrid class";
+    println!(" our school desc: {}", name_of_school);
+    name_of_school
+}
+
diff --git a/src/intro_to_felt.cairo b/src/intro_to_felt.cairo
new file mode 100644
index 0000000..d3ca719
--- /dev/null
+++ b/src/intro_to_felt.cairo
@@ -0,0 +1,8 @@
+// Please note - Security considerations for felt252
+// never use felt252 to perform arithmethic operations
+// the max char length for felt252 is 31
+pub fn run() -> felt252 {
+    let x = 'SAY GM!';
+    println!("x value here: {}", x);
+    x
+}
\ No newline at end of file
diff --git a/src/intro_to_u16.cairo b/src/intro_to_u16.cairo
new file mode 100644
index 0000000..41dca72
--- /dev/null
+++ b/src/intro_to_u16.cairo
@@ -0,0 +1,11 @@
+use crate::utils::low_to_high;
+//converting from low to high
+pub fn run(x: u8, y: u8) -> u16 {
+    let result: u16 = low_to_high(x) + low_to_high(y);
+    result
+}
+
+//converting from high to low
+fn high_to_low(x: u16) -> u8 {
+    x.try_into().unwrap()
+}
\ No newline at end of file
diff --git a/src/intro_to_u8.cairo b/src/intro_to_u8.cairo
new file mode 100644
index 0000000..1e91f2e
--- /dev/null
+++ b/src/intro_to_u8.cairo
@@ -0,0 +1,8 @@
+// integers are basically divided into 2:
+// uint - u8, u16, u32, u64, u128, u256, usize
+// int - i8, i16, i32, i64, i128, i256
+pub fn run(x: u8, y: u8) -> u8 {
+    // x + y // implicit return
+    assert(x + y <= 255, 'exceeds');
+
+}
\ No newline at end of file
diff --git a/src/student_registry.cairo b/src/student_registry.cairo
index 9a405a3..ac53c74 100644
--- a/src/student_registry.cairo
+++ b/src/student_registry.cairo
@@ -22,7 +22,7 @@ mod StudentRegistry {
     use starknet::storage::{
         StoragePointerReadAccess, StoragePointerWriteAccess, StoragePathEntry, Map
     };
-    use crate::errors::Errors::{NOT_ADMIN, ZERO_ADDRESS};
+    use crate::errors::Errors::{NOT_ADMIN, ZERO_ADDRESS, EMPTY_STRING, ZERO_VALUE, SAME_ADDRESS};
 
     #[storage]
     struct Storage {
@@ -51,7 +51,12 @@ mod StudentRegistry {
         ) {
             // validation to check if student account is valid address and  not a 0 address
             assert(!self.is_zero_address(_account), ZERO_ADDRESS);
-            assert(_age > 0, 'age cannot be 0');
+            let _admin = self.admin.read(); 
+            assert(_account != _admin, SAME_ADDRESS);
+            
+            assert(_age > 0, ZERO_VALUE);
+            assert(_name != 0,  EMPTY_STRING);
+            assert(_xp != 0, ZERO_VALUE);
             let student = Student {
                 name: _name, account: _account, age: _age, xp: _xp, is_active: _is_active
             };
diff --git a/src/utils.cairo b/src/utils.cairo
new file mode 100644
index 0000000..831bbd3
--- /dev/null
+++ b/src/utils.cairo
@@ -0,0 +1,4 @@
+// util function to convert u8 to u16
+pub fn low_to_high(x: u8) -> u16 {
+    x.into()
+}
\ No newline at end of file