Tisch
Minutes and seconds are 1, and there are three hands on the clock face. They are (hour hand), (minute hand) and (second hand), of which the fastest is (second hand) and the slow is (hour hand).
2. There are (12) numbers, (12) large squares and (60) small squares on the clock face; There are (1) large cells between every two numbers, that is, (5) small cells.
3, clockwise 1 grid is (1) hours; It takes (5) minutes to walk 1 square and (1) minutes to walk 1 square. It takes (5) seconds for the second hand to go 1 and (1) seconds for the second hand to go.
4. When the hour hand goes 1, the minute hand just goes (1) laps, and the minute hand goes 1 laps for (60) minutes, that is, (1) hours. Clockwise 1 turn, minute hand (12 turn).
5. The minute hand goes 1, the second hand just goes (1) laps, and the second hand goes 1 laps for (60) seconds, which is (1) minutes.
6. When the hour hand turns from one number to the next, it is (1 hour). The minute hand moves from one number to the next (5 minutes). The second hand turns from one number to the next (5 seconds).
7. The time when the hour hand and the minute hand are at right angles on the clock face is (3 o'clock sharp) and (9 o'clock sharp).
8. Formula. (The advance rate between every two adjacent time units is 60)
1 = 60min1min = 60s.
Half an hour =30 minutes, 60 minutes = 1 hour
60 seconds = 1 minute 30 minutes = half an hour.
Addition and subtraction within 10 thousand
1, know the integer thousand (memory: 10 thousand is ten thousand)
2. Read and write numbers (write Chinese characters when reading and Arabic numerals when writing numbers).
No matter whether there is a zero or several zeros at the end of a number, this zero will not be read.
② There is a zero or two consecutive zeros in the middle of a number, and both of them read only one zero.
3. Comparison of figures:
① Numbers with different digits are larger, and those with more digits are larger.
(2) Compare the sizes of numbers with the same number of digits. First, compare the high-order numbers of these two numbers. If the high digits are the same, compare the next digit, and so on.
4. Find the approximate value of a number:
Memory: Look at the last digit, if it is 0-4, use the four-shed method, if it is 5-9, use the five-in method.
The third digit is 999, the third digit is 100, the fourth digit is 9999, and the fourth digit is 1000. The larger three digits are smaller than the smaller four digits 1.
5, the minuend is a three-digit continuous abdication subtraction steps:
① When the columns are vertical, the same numbers must be aligned;
(2) When subtracting, which digit is not reduced enough will be1of the previous digit; If the previous digit is 0, it is 1 of the previous digit.
6. Pay attention to the middle 0 when doing the problem, because it is abdicated continuously, so you should retreat from one hundred to ten at 10, and then from ten to one at 10, and lend one, so there are only nine left in the ten, not 10. (Sum of two three digits: it may be three digits or four digits. )
7. Formula
Sum = Addendum+Another Addendum
Appendix = Sum-Another Addendum
Subtraction = minuend-difference
Negative = negative+difference
Difference = minuend-minuend
extreme
Measure 1. In daily life, a small number of items can be used as units (millimeters, centimeters, decimeters); Large objects are usually measured in meters; Generally, the unit for measuring long distances is (km), also called (km).
2. There are (10) units in the length of 1 cm, and the length of each unit (equal) is (1) mm. ..
3. 1 The thickness of coins, rulers, magnetic cards, buttons and keys 1 min is about1mm..
4. When calculating the length, you can only add or subtract the same length unit.
Tip: When converting the length unit, change the large unit to the small unit and add 0 at the end of the number (if there are several 0s in the relationship, add several 0s); Changing a small unit to a large unit will remove the zeros at the end of the number (if there are several zeros in the relationship, remove several zeros).
5. The relationship between length units is as follows: (the propulsion rate between every two adjacent length units is 10).
(1) The rate is 10:
1 m = 10 decimeter, 1 decimeter = 10 cm,
1 cm = 10mm,10 decimeter = 1 m,
10cm = 1 decimeter,10mm = 1 cm,
② The propulsion rate is 100:
1 m = 100 cm, 1 decimeter = 100 mm,
100 cm = 1 m, 100 mm = 1 decimeter.
③ The propulsion rate is 1000:
1 km = 1 000m,1km = =1000m,
1000m = 1km， 1000m = 1km。
When we express the weight of an object, we usually use (mass unit). In life, the weight of lighter items can be measured in grams. According to the quality of general goods, it is usually a unit (kg); Measure the mass of heavy or bulk goods, usually in tons.
Tip: in the conversion of "ton" and "kilogram", converting tons into kilograms means adding three zeros at the end of the number;
Converting kilograms into tons is to remove the three zeros at the end of the number.
7. The ratio of two adjacent mass units is 1000.
1 ton = 1 000kg1kg =1000g
1000kg = 1 ton1000g = 1 kg
Understanding of the times
1. Find how many times one number is another number, divided by: one number ÷ another number = multiple.
2. Find the multiple of a number by multiplication: this number × multiple = several times this number.
Multiply multiple numbers by one number.
1, estimated. (Find the approximate multiple digits first, and then calculate. Such as 497×7≈3500)
2.① Multiply 0 with any number to get 0; ② Multiply 1 by any number other than 0 to get the original number.
3. If there are several zeros at the end of the factor, add several zeros at the end of the product.
4. Three digits multiplied by one digit: the product may be three digits or four digits.
Formula: speed × time = distance
Number of people in each car × number of cars = number of people in the whole car.
5. (About) Application:
(1) if there is "about" in the condition, but there is no "about" in the question, find the exact number. →(=)
(2) There are no conditions, but "about" appears in the question. Find out the approximate figure and use the estimate. →(≈)
(3) Conditions and problems are "about". Find approximate figures and use estimates. →(≈)
Tisso
A quadrilateral 1, a closed figure with four straight sides and four corners, is called a quadrilateral.
2. Features of quadrilateral: It has four straight sides and four corners.
3. Features of rectangles: Rectangles have two lengths, two widths, four right angles and equal opposite sides.
4. Characteristics of a square: it has four right angles and four equal sides.
5. Rectangular and square are special parallelograms.
6, the characteristics of parallelogram:
(1) The opposite sides are equal and the diagonal lines are equal.
② Parallelogram is easy to deform. (Triangle is not easy to deform)
7. The length of a closed graph is its perimeter.
8. Formula.
Circumference of a square = side length ×4
Side length of a square = perimeter ÷4,
The circumference of a rectangle = (length+width) ×2
Length of rectangle = perimeter ÷2- width,
Width of rectangle = perimeter ÷2- length
A preliminary understanding of scores
1. Divide an object or figure into several parts on average, and take some of them, which is the score of the object or figure.
2. The more shares a whole is divided equally, the smaller the number each share represents.
3.① The numerator is the same, but the fraction with small denominator is large, and the fraction with large denominator is small.
(2) The denominator is the same, the numerator is large, and the numerator is small.
4.① Addition and subtraction of fractions with the same denominator: the denominator is unchanged, only the numerator is added and subtracted.
② Fraction minus 1: 1 can be regarded as a fraction, whose denominator is the denominator of subtraction, and the denominator of the numerator is the same.