Using each of the cards below once, what is the closest number to -64.28 that you can make?
3
7
9
.
5
The closest number to -64.28 that you can make using each of these cards once is -64.35.
Explanation:
Starting with the largest digit, we can use the 7 to create the number -70. Then, we can use the 3 to add 0.03 to get -69.97. Next, we can use the 5 to subtract 0.05 to get -70.02. Finally, we can use the 9 to add 0.09 to get -64.28. However, since we cannot use any card twice, we have to adjust the previous digits. We can remove the 0.02 by using 3 to add 0.03 to get -64.95. Then, we can remove 0.07 by using 7 to subtract 0.07 to get -64.28, which is the desired number. However, we can still use the 5 to subtract 0.05 to get -64.33 and the 9 to add 0.09 to get -64.19, so the closest number is -64.35.