Round 345,409 to the nearest ten thousand

In the ten thousand place, there is a 4. Look to the right of the four and you see a 5. The rule is, if it's 4 or under you round down. If it's 5 or over you round up. Since it's a 5, we go up. You add 1 to the 4 and you get 150,000 since you turn the rest into 0s.