Ten digit telephone number has a form (XYZ) - ABC-DEFG. In the particular state there are 4 possible area codes (404, 470, 678, and 770). The digit A is restricted to a number 2 through 7. The digits B, C, and D can be any number but they cannot repeat. E, F, G have no restrictions. How many phone numbers are possible with these restrictions?

im not sure but i rember having this question i think its 770

Step-by-step explanation:

(n^3 - n)

= n(n-1)(n+1)

since it is divisible by 3 and 2 ,because it is a multiple 3 consecutive number

if, n-1 is odd then n+1 is also odd, then it is a multiple of 9

but if, n-1 is even then n+1 is also even, then it is a multiple of 4

so, largest multiple = max(9*2, 4*3) = max(18, 12) = 18

-14

step-by-step explanation:

2x2 – 2(x+4)

=2x2-2（5+4）

=4-2×9

=4-18

=-14