¿Cuántos tokens se transfieren realmente cuando usamos decimales?

Tengo un código a continuación y cuando estoy transfiriendo 1,695,000,000 a una dirección en particular, en realidad se están transfiriendo 0.000000001695. ¿Por que es esto entonces? ¿Eso significa que para transferir 1.695 mil millones de tokens necesito poner 18 ceros iniciales? Aquí está el código:

function transfer(address _to, uint256 _amount) public returns (bool success) {
    require(_to != address(0));
    require(balances[msg.sender] >= _amount && _amount > 0
        && balances[_to].add(_amount) > balances[_to]);

    // SafeMath.sub will throw if there is not enough balance.
    balances[msg.sender] = balances[msg.sender].sub(_amount);
    balances[_to] = balances[_to].add(_amount);
    Transfer(msg.sender, _to, _amount);
    return true;
  }


contract SomeToken is MintableToken, BurnableToken {
     string public name ;
     string public symbol ;
     uint8 public decimals = 18 ;

     /**
     *@dev users sending ether to this contract will be reverted. Any ether sent to the contract will be sent back to the caller
     */
     function ()public payable {
         revert();
     }

     /**
     * @dev Constructor function to initialize the initial supply of token to the creator of the contract
     * @param initialSupply The initial supply of tokens which will be fixed through out
     * @param tokenName The name of the token
     * @param tokenSymbol The symbol of the token
     */
     function SomeToken(
            uint256 initialSupply,
            string tokenName,
            string tokenSymbol
         ) public {
         totalSupply = initialSupply.mul( 10 ** uint256(decimals)); //Update total supply with the decimal amount
         name = tokenName;
         symbol = tokenSymbol;
         balances[msg.sender] = totalSupply;

         //Emitting transfer event since assigning all tokens to the creator also corresponds to the transfer of tokens to the creator
         Transfer(address(0), msg.sender, totalSupply);
     }
}