Rounding method: 0, 1, 2, 3, 4, no carry, 5, 6, 7, 8, 9 carry.

Step-by-step method: Step-by-step method is to add the approximate value obtained in this way to the last number of the retained part after removing the redundant number.

Truncation: Truncation is a common mathematical method to remove the decimal part of a number and take its integer part. Its value is approximate and is often used in life.

Quantity unit estimation method: use real-life objects to perceive quantity units and actually experience the size of data.

The skill formula of division estimation in the third grade of primary school

First look at the highest two digits of dividends. If it is greater than the divisor, it can be a quotient. If it is several times, it can be quotient. Compared with divisor, remainder and unit can be quotient, but they can't be quotient at the end of operation.

If the highest two digits of the dividend are less than the divisor, you should look at one more digit and drag it down.

Three digits, division, hundreds of divisors, write a few if the quotient is enough, and don't cross if the quotient is not enough. One hundred digits constitute a new number, and several vendors are not bad. Business should be written in ten places, and if it is sloppy, it will fall behind. Don't blame one writer, there is more than one business. If the quotient is not enough, fill in zero and leave one digit as the remainder.