Compatible number can be defined as,

"The numbers which are close to the actual numbers, and can be easily added, subtracted or divided orally are known as compatible numbers."

These numbers are used for carrying out some basic mathematical functions. For example, if you are given the expression, 13 รท 3.6 to calculate, then it will be difficult for you. However, if you take 12 and 4 and divide 12 by 4, then you can orally do this. The value which you will get after dividing 12 by 4 will be closer to 13 divided by 3.6. This can give you the nearest estimation mentally.

"The numbers which are close to the actual numbers, and can be easily added, subtracted or divided orally are known as compatible numbers."

These numbers are used for carrying out some basic mathematical functions. For example, if you are given the expression, 13 รท 3.6 to calculate, then it will be difficult for you. However, if you take 12 and 4 and divide 12 by 4, then you can orally do this. The value which you will get after dividing 12 by 4 will be closer to 13 divided by 3.6. This can give you the nearest estimation mentally.