Pick a reference number and see for yourself whether it's included in a range, and which way an estimated value goes.
At least/at most and more than/less than both mean bigger or smaller than a number, but there's an important difference. At least/at most include the reference number itself, while more than/less than do not. For example, "age 12 or older" includes age 12, but "older than 12" starts at 13.
Rounding up, rounding down, and rounding to the nearest are three ways to make an estimate. Rounding up always goes to the bigger value, rounding down always goes to the smaller value, and rounding to the nearest picks whichever side is closer, using 5 as the cutoff. A store rounding a price to the nearest 100 won, or a fee getting rounded up to a fixed unit, both use this same idea.
Change the reference number and the wording, and watch whether the dot on the number line is filled in or empty. Then drag the slider to move the digit place and compare how the value changes.
① Number Ranges — At Least / At Most / More Than / Less Than
Pick a reference number, then choose one of the four expressions. Whether the reference number itself is included changes.
② Rounding Up, Down, and to the Nearest
Pick a number and a digit place, and compare how rounding up, down, and to the nearest differ, all at once.