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If a, b, c and d are replaced by four different digits from 1  to 9 , inclusive, then what's the largest possible value for a.bc + 0.d

 Dec 21, 2022
 #1
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The answer is \(9.87 + 0.6 = 10.47\).

 Dec 21, 2022
 #2
avatar+559 
+7

I got 10.56

dolphinia  Dec 21, 2022
 #3
avatar+1317 
+2

a.bc + 0.d, obviously a is the biggest, so we choose a to be 9.

b must be the second biggest because b is in the .1s digits, so we choose it to be 8. However, Guest made a little mistake because 0.d must be the second or third biggest as it is also in the .1s digits, and lastly c is the smallest, but the biggest one we haven't picked yet.

Thus 9.86 + 0.7 or 9.76 + 0.8 would both be the biggest. As dolphinia got, it would be 10.56.

 Dec 23, 2022

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