Another quick and fun example of everyday deceptively LARGE numbers action. I recently used my first ‘virtual’ or temporary credit card, for a USA purchase. This site generated a single-use card, pre-loaded with $n USA (but it couldn’t be recharged). Mmm, says the mathematician in me, how many cards could each person on Earth have?
Some in the head, approximate numerical pondering followed:
(a) 16 numerical digit card number. 1o16 combinations (a 1 followed by 16 zeros)
(b) 7 billion people on Earth. 7x(109). That 7 is near 10, so I’ll round the whole thing up to 1010
Thusly dividing (a)/(b) we can have 10 (16-10) each (remember your exponential maths?). Which is 106 That is 1 million cards each.