Answer:
600
Step-by-step explanation:
To round your answer, you check the tenths place to see if it is under 5 or above 5. If it is under 5, your answer will stay in the number the hundreds place is in currently. If it is above 5, you will add one to the hundreds place.
312: there is one in the tenths place, so it will stay as 300.
138: there is three in the tenths place, so it will stay as 100.
207: there is a zero in the tenths place, so it will stay as 200.
If you are doing it with the one's place, it is the same method. Either round up or down.
300 + 100 + 200 = 600
The answer is 600.
