You used a different rule for 289 (start by multiplying the first and third digits) compared to the other two (start by multiplying the first and second digits). Why was that?

for 289 I took the last element 9 and multiplied with the remaining
for 456 I took the first element 4 and multiplied with the remaining
for 748 I took the middle element and multiplied with the remaining

so for 387 i again took the last element

Its just my very random guess and I am not sure if this is the solution.