Answer:
When rounding you want to take the number behind the one that you are looking for and see if it is either 5 or greater, or 4 and lower
If you're number is 5 or greater than you would round up
If you're number is 4 or lower than you would round down
In 345,972 the digit in the hundreds place is 9, so we are looking at the digit behind that which is 7, so you would round up because 7 is greater than 5
You would then add one to 9 which is 10, so you would leave the 0 and add 1 to the 5 in the thousands place
Your rounded answer would be 346,000
Hope this helps ;)
Explanation: