SOLUTION: Suppose you want to make $5 using exactly 100 common US coins. Easy, you say: just use nickels (5 cents each). But I say, no - we have NO nickels, only pennie

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Question 492814: Suppose you want to make $5 using exactly 100 common US coins.
Easy, you say: just use nickels (5 cents each). But I say, no -
we have NO nickels, only pennies (1 cent), dimes (10 cents) and
quarters (25 cents) - is it possible to make $5 now with exactly
100 of these coins? Why or why not?

Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Start with 20 quarters, and only use pennies
until you can reach at least 100 coins
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20 quarters + 0 pennies = 20 coins
19 quarters + 25 pennies = 45 coins
18 quarters + 50 pennies = 68 coins
17 quarters + 75 pennies = 92 coins
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So there must be at THE MOST 16 quarters
16 quarters + 100 pennies = 116 coins
16 quarters + 1 dime + 90 pennies = 107 coins
16 quarters + 2 dimes + 80 pennies = 98 coins
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15 quarters + 5 dimes + 75 pennies = 95 coins
15 quarters + 4 dimes + 85 pennies = 104 coins
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10 quarters + 15 dimes + 100 pennies = 125 coins
10 quarters + 20 dimes + 50 pennies = 80 coins
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I think this is as close as you will get. The problem is that
both the sum of money you need and the number of
coins both are multiples of 5, and that means each of
the number of quarters, dimes and pennies all have to
be divisible by 5, and all together, by 10.
So, +15+ or +10+ quarters is allowed, but neither
will give you +100+ coins