Estimating the size of a number or quantity that is not carefully is just a guess amounts or quantities with the eyes only. There is no need to use a calculator or counting measure.
The estimate is the size or volume of unwanted exhaustive. Is mere conjecture amount or quantity by sight only. No need to use a calculator to measure or count in any way.
Estimation of a magnitude number or quantity, not thorough. Are only estimates amount or quantity with eyes only. There is no need to use the calculator, or counting meter.