Natural constant, a constant in mathematics, is an infinite acyclic decimal and a transcendental number, and its value is about 2.7 1828.

As a mathematical constant, e is the basis of natural logarithmic function. Sometimes called Euler number, named after the Swiss mathematician Euler; There is also a rare name, Napier constant, to commemorate the Scottish mathematician John Napier? (John Napier) introduced logarithm. It is one of the most important constants in mathematics, just like pi and imaginary units I and E.

Extended data

Estimation method:

1. Four five items: 0, 1, 2, 3, 4, no carry, 5, 6, 7, 8, 9, carry.

2.？ Step by step: Step by step is to add 1 to the last digit of the reserved part after removing the redundant digits. The approximation thus obtained is a residual approximation (i.e., greater than the exact value).

For example, a sack can hold 200 Jin of wheat, and there are currently 880 Jin of wheat. How many sacks do you need to wrap it? When 880 is divided by 200, the quotient is 4, and the remainder is 80, that is, 4 sacks are not enough, and 5 sacks are needed.

3. Truncation method: Truncation method is a commonly used mathematical method, which removes the decimal part of a number and takes its integer part, and its value is approximate (that is, less than the exact value), which is often used in life.

4. Quantity unit estimation method: use real-life objects to perceive quantity units, and what is the size of actual empirical data.