Change for a Dollar

 


What is the largest amont of money, obviously in coins each less than one dollar, you can
have and not be able to make change for a dollar?

Using the example as a starting point

Consider 3 quarters and 3 dimes. You have $1.05 but you can not make change for a dollar.

First thoughts:

I thought of initial constraints on each coin less than one dollar

3 quarters can not make change for a dollar ($.75)

9 dimes can not make change for a dollar ($.90)

19 nickels can not make change for a dollar ($.95)

99 pennies can not make change for a dollar ($.99)

Possible methods

Algebra?

.25Q + .10 D + .05 N + .01 P < 1

If Q =3, then D < 5.

 

Trial and error method?

This worked for me.

Spreadsheet

More definitive.

What combinations of coins will give the maximum?

 

The highest amount of money I got was $1.19

3 quarters + 4 dimes + 4 pennies = $1.19


 

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