1, the meaning of score: divide a whole into several parts on average, and the number representing 1 or several parts is the score. Representative: Divide a whole into five parts on average, and take two of them. Representation: divide a whole into four parts on average and take one of them. 2. Method of comparing sizes: (1) The numerator is the same, and the score with smaller denominator is larger. (2) The denominator is the same: the larger the numerator, the greater the score. 3. Add and subtract fractions with the denominator. The denominator remains the same, and only the numerator is added and subtracted. The denominator means to divide a whole into several parts on average, and the numerator means to take several parts. 5. In the ID code, the 17th code indicates gender: odd male and even female. 6. Items A and B, only items A and C, only meetings A and B (1). Find the total number of people: A+B-C (2) How many people are there in Meeting A or Meeting B: A+B-C or (A-C)+(B-C) Rectangular and Square 65438+. 2. Features of quadrilateral: It has four straight sides and four corners. 3. The characteristics of a rectangle: the opposite sides are equal and there are four right angles. 4. Features of a square: all four sides are equal, and there are four right angles. 5. The length of a closed figure is its circumference. 6. The perimeter of a rectangle = (length+width) ×2 The perimeter of a square = side length × 4 7. Cut out the largest square in the rectangle, and the width of the rectangle is the side length of the square. How many times is one number more than the other? Calculate by division: how many times is one number ÷ another number = multiple 36? 36÷4=9 Given that several times a number is a, find this number. Calculate by division: A÷ multiple = This number is known. The multiple of a number is 35. How did you find this number? 35÷5=7 What is the multiple of a number? Multiplication calculation: What is a number × multiple = 6 times of the result 9? Addition and subtraction within 9× 6 = 540000 1, maximum and minimum digits: the maximum digit is 9 and the minimum digit is 0. The maximum digit is 99, the minimum digit is 10, the maximum digit is 999, the minimum digit is 100, and the maximum digit is 9999. The smallest four digits are 1000, the largest five digits are 99999, and the smallest five digits are 10000. The largest three digits are smaller than the smallest four digits 1. 2. When adding and subtracting with a pen: the same numbers should be aligned; From the number of units. Which number adds up to 10, and then enter the previous number1; Where the number of digits is not reduced enough, take 1 from the previous digit as 10, and then reduce it after adding the standard; If the previous digit is 0, it is 1 of the previous digit. 3. Sum of two three digits: it may be three digits or four digits. 4. Addition formula: appendix+appendix = and-another appendix = appendix 5. Subtraction formula: minus-meinu = difference+meinu = minus or minus = difference+meinu-difference = meinu 6. When calculating orally, for example: (1)35+48, calculate 35 first. (2)72-28, first 72-20=52, then 52-8=44 or 72-30=42, then 42+2=44 7. There are "approximate", "approximate", "estimate" and "estimate" in the question. Minutes and seconds are 1. There are three hands on the clock face, namely hour hand, minute hand and second hand. The second hand is the fastest and the hour hand is the slowest. (The hour hand is the shortest and the second hand is the longest) 2. Measure a short time, usually in seconds. Seconds are smaller units of time. The longest and thinnest hand on the clock face is the second hand. It takes 1 second for the second hand to walk a small square. 4. Stopwatch: generally used in sports to record time in seconds. 5. Common time units: hours, minutes and seconds. 6. Time units: hours, minutes and seconds, and the forward speed between every two adjacent units is 60. 1 hour =60 minutes 1 minute =60 seconds and half an hour =30 minutes and 30 minutes = half an hour 7. The minute hand walks once, and the hour hand walks a big grid, which is 1 hour. The second hand turns, and the minute hand occupies a small space. 1 minute. 8. To calculate a period of time, you can subtract the start time from the end time.