To round up a number, you will add one value to the digit if the lower digit number is 5 or more. If the number is lower than 5, then you don't have to add one value.
In this case, you need to round up to hundred thousand. So, you need to look at the ten thousand digit which was 6. Since it was more than 5, you can add 1 value to the ten thousand digit. Then 362,584 will become 400,000
The triangles are similar because corresponding angles are congruent, however no congruency statement can be made because the side lengths are unknown.
