Answer
It makes equations easy so solve by mentally adding and subtracting numbers.
Explanation
Estimation means getting something close to the answer. Estimating can also be called approximating.
For example 3.4 can be estimated to 3 in whole number.
When adding and subtracting decimals, estimation makes it easier. Operations can be done offhead without counting or using objects. Estimation is very helpful especially with middle school students who are actively doing addition and subtraction questions.
An equation can be solve mentally when allowed to estimate. For example,
1) 9.7 - 3.8 = 10 - 4
= 6.
2) 39.93 + 60.09 = 40 + 60
= 100.
