My daughter at school as the foolowing problem to answer?

Question

if 2178 x 4 = 8712 therefore the same numbers in reverse, what are the 4 digits number x 9 give the same results and how did you arrive to the answer

Answer 1

For a 4-digit number, let a, b, c, and d be the digits, so we get: 9*(1000*a+100*b+10*c+d) = 1000*d + 100*c + 10*b + a

Simplifying: 8999*a + 890*b = 10*c + 991*d

This implies that d = 10 - a, by looking at the last digits, which we substitute, and get: 9990*a + 890*b = 10*c + 9910

When we divide by 10, we get 999*a + 89*b = c + 991

This implies that a = 1, so 89*b = c - 8

This implies that b = 0 and c = 8, and there is only one solution: 9*1089 = 9801.

Answer 2

France, I would bet my monitor that your mother DID NOT write this. What exactly is "the same result"? If you wanted the product of something x 9 to get 8712, something will not be a 4-digit number.

Let's be more honest, and at the same time, use the English more correctly.

Answer 3

there is no possible way. what grade is your daughter in because i am in advanced 6th math and my teacher could not answer that question

Answer 4

it would be cheating to help you. im really sorry. im tempted to ask for help on my school work all the time, but that is entirely unfair. if she passes b/c i helped her, she doesnt deserve to pass, if she passes b/c she figured out all the answers, shes fine. but really, dont ask for people to do the work for you.

Answer 5

1111?

seems possibly simple enough to me hehe

Answer 6

No fooling

Answer 7

wish i could help but sorry i don't know.

Answer 8

tell her to do her own homework

Answer 9

i can help, but in which grad she is?

Answer 10

0-o

wish i could help

but i dont know wat your talking about