When we round or approximate a number, there is always a small difference, or error, between the rounded or approximate number and the actual number.
Error estimating is a way to find out how much the rounded or approximate number is different from the actual number.
For example, let's say you're trying to estimate the number of candy pieces in a jar. You count the candies in a few small groups and then multiply that number by the total number of groups to get an estimate. If your estimate is 100 candies, but there are actually 105 candies in the jar, then the error is 5 candies.
It's important to keep in mind that error can be positive or negative, meaning the rounded or approximate number can be either bigger or smaller than the actual number.
Knowing the error can help you get a better understanding of how accurate your rounding or approximation is. It's a good habit to always estimate the error when working with rounded or approximate numbers, especially in real-world problems.