bbyggigi6634 bbyggigi6634
  • 04-09-2017
  • Mathematics
contestada

How many 7 digit phone numbers are there assuming the first digit can't be a 0 or a 1?

Respuesta :

Аноним Аноним
  • 04-09-2017
The first digit can be any one of the numbers 2-9 That a total of 8 numbers.

The next 6 digits can be any permutation of 6  from the numbers  0 to 9.
(10 numbers)

nPr  =  n! / r!

so here we have  10P6  = 10! / 6!  =  10*9*8*7  =  5040

So final answer  is 8 * 5040 = 40,320
Answer Link

Otras preguntas

a maze at a country fair is made from 275 bales of hay. the maze at the state fair is made from 4 times as many bales of hay. how nany bales of hay are used for
the wires inside a cable each have there own plastic insulation .why does the insulasion have diffrent colours
how did the French and Indian war draw the colonist closer together but increase friction with Britain
Solve For V 2v + 18 = 16 - 4 ( v + 7 )
How did South Carolina respond to the election of Abraham Lincoln as president in 1860?
speed or velocity are more helpful to a pilot why
Which is an effective way to resist peer pressure to do something you're uncomfortable doing?
A parallelogram can have no more than two obtuse angles
Bacteria from the soil absorb nitrogen from the air and convert it into ammonium. This is an example of _____. the hydrologic cycle nitrogen fixation assimilati
Several types of ________ are used to produce yogurt. A. molds B. yeasts C. protozoa D. Bacteria