How to get the user entered input value to do calculation?
Store the loan amount in session when user submit the form1, and when rendering the form take that session value and display a suggestion field.

The code will be like below,

function form1_submit($form, &amp;$form_state) {
  $_SESSION['loan_search_amount_field_value'] = $form_state['values']['loan_search_amount_field_name'];
}

function form2() {
  $form = array();
  $loan_amount = $_SESSION['loan_search_amount_field_value'];
  //db_query using $loan_amount
  //$db_result_array = db_query();
  $form['load_options'] = array(
    '#description' =&gt; t('Loan options'),    
    '#type' =&gt; 'select',
    '#title' =&gt; t('Field type'),
    '#options' =&gt; $db_result_array,
    '#size' =&gt; 2,
  );      
  return $form;
}