What is "estimation" and how to estimate it?

Just make a rough estimate first. For example, 64x9 can first estimate 9 as 10, then calculate it as 640, then calculate it vertically, and then calculate it as 57.

Pen calculation is a method of writing formulas or calculating grass with a pen, which is the most commonly used calculation method in mathematics. Related calculation methods include mental calculation, oral calculation and so on.

Extended data:

Estimation method:

1, rounded: 0, 1, 2, 3, 4, none carry, 5, 6, 7, 8, 9, carry.

2. One-to-one method: One-to-one method is to add 1 to the last bit of the reserved part after removing redundant figures. 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 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: What is the size of actual empirical data with real-life objects to perceive quantity units?

Baidu encyclopedia-written calculation

Baidu Encyclopedia-Estimation