Help Me plase

Thank you

Printable View

- Mar 30th 2007, 12:49 AMveltelHow do you make $1.00 with 21 coins?
Help Me plase

Thank you - Mar 30th 2007, 03:39 AMmalaygoel
10*8 + 2*7 + 1*6=100

- Mar 30th 2007, 05:03 AMtopsquark
What coins are these?

I don't have anything better than trial and error, but I'd set it up like this:

Let there be q quarters, d dimes, n nickels, and p pennies. Then:

100 (cents) = 25q + 10d + 5n + 1p

and

q + d + n + p = 21

Solve the second equation for p:

p = 21 - q - d - n

and insert this value of p into the first equation:

100 = 25q + 10d + 5n + (21 - q - d - n)

79 = 24q + 9d + 4n

I would start with the assumption there are 3 quarters (which almost certainly won't work), and work my way down. It could take a while without some more insight, which I'm afraid I can't offer you. :(

-Dan - Mar 30th 2007, 08:48 AMThePerfectHacker
I am not sure what coins are you using.

If you have a lot of coints it becomes the Frobenius Coin Problem. - Mar 30th 2007, 12:55 PMSoroban
Hello, veltel!

We have: . Q + . D .+ . N + P .= . 21

. . .and: .25Q + 10D + 5N + P .= .100

Subtract: .24Q + 9D + 4N .= .79

From here, I found four solutions:

. . 2Q, 3D, 1N, 15P

. . 1Q, 3D, 7N, 10P

. . . . . 7D, 4N, 10P

. . . . . 3D, 13N, 5P