Answer :

a thousandth = 1/1000 = 0.001
round 4th decimal place = 5
5 and over rounds up, under 5 rounds down
so answer is 3,989.237

a thousandth = 1/1000 = 0.001

round 4th decimal place = 5

5 and over rounds up, under 5 rounds down

so answer is 3,989.237