Formula calculation is the operation of recursive equation calculation, which is divorced from the original calculation and completely writes out the calculation process, that is, from the longitudinal calculation.

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When calculating mixed operations, it is generally calculated from left to right, and a formula is calculated step by step.

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Calculate multiplication and division first, then addition and subtraction. In the continuous calculation of multiplication and division, it should be calculated from left to right.

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When you encounter parentheses, you must first calculate the inside of the parentheses. There are many kinds of brackets, which are calculated in the order of first bracket, then bracket and finally brace.

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I. Calculation of parting

( 1)6×409-2300 (2)528+323-60×8 (3) 1 100×5-(560+690)

(4)7×(555-377) (5)200-(76+40×3) (6)220-(45×3-60)

Second, the column calculation

(1) A number is 68 times that of 145. What's this number?

(2) What is the difference between the products of180 and 175 and 124?

(3) What is the product of 5 times 37 minus 55 times 8?

Third, solve the problem.

1. Girls in the running group 18, boys 17. There are three times as many people in the Wushu group as in the running group. How many people are there in the Wushu group?

2.368 students are divided into four groups to plant trees. There are 98 students in the first three groups. How many students are there in the fourth group? (5 points)

3. Zhang Cun plans to dig ditches 1.000m, and dig ditches 1.24m every day. After seven days of digging, how many meters are left?

4. Fruit shops buy back apples 150kg and pears 123kg. The number of oranges bought back is four times that of apples and pears. How many Jin of oranges does the fruit buy back?