Important and difficult knowledge points of mathematics in the sixth grade graduation examination of primary school
Xingcheng recreation and sports
Basic concepts:
The travel problem studies the movement of objects and the relationship among speed, time and distance.
Basic formula:
Distance = speed × time; Distance ÷ time = speed; Distance/speed = time
Key questions:
Determine the position and direction during the movement.
Meeting problem: speed sum × meeting time = meeting distance (please write other formulas)
Catch-up problem: catch-up time = distance difference ÷ speed difference (write other formulas)
Flow problem: downstream flow range = (ship speed+current speed) × downstream time.
Upstream stroke = (ship speed-water speed) × upstream time
Downstream speed = ship speed+current speed
Current speed = ship speed-water speed
Still water velocity = (downstream velocity+upstream velocity) ÷2
Water velocity = (downstream velocity-upstream velocity) ÷2
Running water problem: the key is to determine the speed of the object, refer to the above formula.
Bridge crossing problem: the key is to determine the moving distance of the object, refer to the above formula.
Main methods: line drawing method.
Basic question:
Given any two quantities of distance (meeting distance and catching distance), time (meeting time and catching time) and speed (speed sum and speed difference), find the third quantity.
People's education printing plate sixth grade mathematics knowledge point book one
Percentage application problem
1, find common percentages, such as: compliance rate, pass rate, survival rate, germination rate, attendance rate, etc. Is to find the percentage of one number to another.
2. Find out how much one number is more (or less) than another. In real life, people often use how much to increase, how much to decrease and how much to save to express increase or decrease.
What percentage of A is greater than B: (a-b) B.
How much is B less than A: (a-b) A.
3. Find the percentage of a number. A number (unit "1") × percentage.
4. What percentage of a number is known? Find this number.
Partial quantity ÷ percentage = a number (unit "1")
5, discount, discount means: a few fold is a few tenths, that is, dozens of percent.
Discount, percentage = fraction, percentage, decimal
20% discount = 20% discount = 8/ 10 = 20% discount =0.8
15% discount = 15% discount = 15% discount or more = 15% discount =0.85.
50% off = 50% off = 5/ 10 = 50% off =0.5= half price.
interest rate
(1) The money in the bank is called the principal.
(2) When withdrawing money, the excess money paid by the bank is called interest.
(3) The ratio of interest to principal is called interest rate.
Interest = principal × interest rate× time
After-tax interest = interest-interest tax payable = interest-interest ×5%
Note: Interest on national debt and education savings is not taxed.
Percentage application problem classification
What percentage of (1)B is A-(A-B) × 100%= what percentage?
(2) What percentage of A is greater than B-(a-b) ÷ b×100%.
(3) How much is A less than B-(B-A) ÷ B × 100%?
Sixth grade mathematics orientation and direction review knowledge points
First, the method of determining the position of the object:
1, find the observation point first;
2. Re-determine the direction (see the included angle of the direction);
3, finally determine the distance (see scale)
Second, the key to describing the road map is to select observation points, establish direction markers and determine the direction and distance.
Third, the relativity of positional relationship:
1, the two places are relative. When describing the positional relationship between the two places, the observation points are different, the narrative direction is just the opposite, and the degree and distance are just the same.
Fourth, the relative position: east-west; North-south direction; East by south-west by north.
Articles about the knowledge points of mathematics in the sixth grade of primary school;
★ Summary of Mathematics Knowledge Points in the Sixth Grade of Primary School
★ Summary of the knowledge points reviewed at the end of the sixth grade mathematics.
★ A Complete Collection of Mathematics Learning Methods and Skills in the Sixth Grade of Primary School
★ Review the knowledge points in the first volume of sixth grade mathematics.
★ Integration of review materials of mathematics knowledge points in grades one to six.
★ Statistical knowledge points of mathematics in sixth grade of primary school.
★ Organize the knowledge points of the sixth grade math review (full version)
★ Summary of sixth grade mathematics knowledge
★ Sort out and summarize the knowledge points of the first volume of mathematics in the sixth grade.