2008 iTest Problems/Problem 15

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Problem

How many four-digit multiples of $8$ are greater than $2008$?

Solution

We can make a list of four-digit multiples of $8$ that are greater than $2008.$ The smallest multiple of $8$ that is larger than $2008$ is $2016,$ so we can start with $2016.$ The largest four-digit multiple of 8 is $9992.$ \[2016, 2024, 2032,  ..., 9984, 9992\] Divide everything in the list by $8:$ \[252, 253, 254, ..., 1248, 1249\] Now subtract $251$ from every member of the list. \[1, 2, 3, ..., 998, 999\] There are $999-1+1=\boxed{999}$ numbers in this list, so there are $999$ four-digit multiples of $8$ that are greater than $2008.$

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