Standard deviation is an important calculation for math and sciences, particularly for lab reports. Standard deviation usually is denoted by the lowercase Greek letter Ï. Here is step by step instructions for calculating standard deviation by hand.
For the Japanese company, see Invoice (company). An invoice, bill or tab is a commercial document issued by a seller to a buyer, relating to a sale transaction and indicating the products, quantities, and agreed prices for products or services the seller had provided the buyer. Payment terms are usually stated on the invoice.
An open invoice remains open until the bill is paid in full. Jupiterimages/Photos.com/Getty Images. When a company purchases a product or service from a vendor or supplier, it generally receives an invoice. An invoice statement serves as a bill for goods or services rendered and details what the company owes.