Lead is also used in ceramic glazes and as a stabilizer in plastics. Lead was used extensively as a corrosion inhibitor and pigment in paints but concerns over its toxicity led to the CPSC in 1977 to ban the use of lead in paint for residential and public buildings.
The first digit assigned to all Visa cards is four, and the second through sixth numbers are connected to the financial institution. Then, either the seventh through 12th numbers, or the seventh through 15th, are the account number, while that final 13th or 16th digit is the check number.
All Visa credit cards start with a 4, MasterCard with a 5, and 6 is dedicated to Discover. The first six digits of your card, including the industry identifier, represent the issuer identification number. This identifies the bank that issued the card. And then, of course, there's your personal account number. This is made up of the seventh digit on -- everything except the last number on your card. The final digit on your credit card is known as the check digit or checksum.. This number is set by something called the Luhn formula, patented by Hans Peter Luhn, an IBM scientist in 1960. It's a formula that uses the numerals in your card's account number to verify that it's valid.