Elementary school maths takes an exam, major child can take an examination of more than 90 minutes, but why cannot a lot of people take an examination of full marks? The reason depends on the detail issue that a lot of knowledge select.
The teacher can be when giving a title in the title set a lot of trap, this is about to inspect the child to understand thorough level to what knowledge nods. These 24 maths take an exam below medium " trap " , it is the commonnest fallible feature in mathematical exam, see you have " in enrol too " !
1. is divided and divide with distinction
A is divided be divided by B with B or A, row type is: A ÷ B
A divides B or use A purify B, row type is: B ÷ A
Dividend is read use afore " except with " , and divisor is read use afore " except " , for example " 15 ÷ 3 " read " 15 except with 3 " or read " 3 except 15 " . 15 except with of 3 " with " be " with " meaning or " take " meaning, "15 except with 3 " can explain to use 3 purify 15. And " 3 divide 15 " , use 3 purify namely the meaning of 15.
The half of round circumference of ≠ of 2. semicircular circumference
These two look be like identical, actually is different, because semicircular circumference is much still,give a diameter.
The relevant computation after 3. roller is ongoing
Is roller scroll a week ongoing how many meters? It is the circumference that begs it.
Roller rolls a week controls the area of the road, beg the side area of platen namely.
4. solves equation problem
Solve equation problem: Minus sign is before bracket, go bracket should change date! Transpose should change date!
5. computation problem: Remember operation order well
6. cord accident compares a problem
The remainder problem of 7. decimal division
0.17 business of 0.52 ÷ are 3, remainder is not 1 however 0.01. "Enlarge dividend and divisor at the same time identical multiple, business is changeless " this word, just say business is changeless, did not concern with remainder, also must not enlarge remainder at the same time.
8. per cent is relevant problem
In the rate that beg XX or the row type of hundred, finally must " × 100% "
9. avoid by all means half half person, tree
In beg total number, total a number, total a tree... when the exercise, the result cannot be mark and fraction. When if you are being done,be being inscribed, appear 32.2 12.5 people, chicken wait such answer a moment, without doubt, be err of which one pace for certain.
10. adapting number notes a problem
Adapt an exact number, do not beg " round " when taking approximation, must " 10 thousand " or " 100 million " the number from the back writes decimal part; Only about or elliptically " 10 thousand " or " 100 million " when the mantissa from the back, just use " round " beg approximation, fine must be written " 10 thousand " or " 100 million " .
The pronunciation that 11. counts greatly
Count pronunciation greatly: Read a few problems of 0
12. approximation problem
For example, the similar number of a number is 10 thousand, this number is ______ greatly most.
A lot of student union are filled 9999, actually right answer is 14999.
The approximation that round reachs, may be not only " 5 enter " must come, still be likely " 4 abandon " must come.
13. sort problem
Problem of numeric size sort: The size that notices the title asks is ordinal
For example, 3.14, π , 22/7 according to from arrange _________ toward small order greatly
Right answer is 22/7> π > 3.14, must not write into 3. 14<π <22/7.
The title asks how to come, fasten blind monkey business. And must keep original number sort.
14. scale problem
Scale problem: Notice the scale of the area
For example, it is in scale 1: On the sand table of 2000, actual area is ____ square metre for the zoology park of 800000 square metre.
Right answer is 0.2, must not write into 400.
A lot of classmates use 800000 + 2000 directly, reached wrong answer. Be sure to keep in mind, scale is apart from on = graph: Be apart from actually, it is the scale of length, pursue namely unit of on 1 length is actual medium 2000 length unit. But the subject drag in arrives area, need the scale of translate into area. Need the scale square of a length, pursue namely unit of on 1 area is actual medium 4000000 areas unit.
Problem of scale of 15. positive and negative
Problem of scale of positive and negative: Did not make clear the meaning of direct proportion, inverse proportion
For example, judge pair of faults: Round area and radius become direct proportion. This is wrong (× ) .
If two volumes product is calm value, become inverse ratio; If the business of two quantities is calm value, become direct ratio. Block a definition strictly, primary problem instead " the square of round area and radius becomes direct ratio " , just be correct.
The problem that 16. compares
Compared problem: Note from beginning to end ordinal
For example, after the 1 /3 that increases it growing by the side of a square, of former square and new square area than be _____ .
Must not write into 16: 9, see well who is those who compare is ditto, who is compare hind, right answer should be 9:16.
17. compares the distinction with ratio
For example, after the 1/3 that increases it growing by the side of a square, the ratio of former square and new square area is ____ .
This problem catchs up with the face is inscribed then different, must not write into 9: 16, right answer should be 9/16.
Ratio is a result, it is a number.
18. does not want leakage to keep an unit
For example, the edge grows the square for 4 centimeters, the area is ___ .
Must not write 16 came to an end, must head an unit, right answer is 16 square centimeter ability is right.
Area problem, the result calculates was opposite, but the unit that did not keep this, be just as the traveler in desert, be in to death yearningly it is nearly by the side of the river that very close.
19. notices the accord of the unit
For example, inscribe together so: The mark on bag of some kind of flour has (25kg ± 50g) mark, this kind of flour is ____kg again most.
See well unit, here Kg and G unit are abhorrent, must not fill 75, right answer should be 25.05. This kind is elementary and wrong, must not make.
Problem of 20. bissextile, non-leap year
Problem of bissextile, non-leap year: Do not understand the concept of bissextile
4 years of one intercalary, hundred years not bissextile, 400 years again bissextile. If an a particular year is the multiple of 4, it is bissextile; It is non-leap year otherwise. But if be to make a particular year of 100 (be like 1900, 2000) , must be the diploid ability of 400 is bissextile, it is non-leap year otherwise.
Issue of 21. average rate
Total time of ÷ of total distance of average rate = , what not be equal to speed is average.
For example, a such problem: Speed of the hill on Xiaoming is 1 meter / second, downhill speed is 3 meters / second, the average rate of hill falls to be ___ on Xiaoming.
If such writing (2=2 of 1+3) ÷ (rice / second) , it is wrong for certain.
Total distance did not tell here, assume first so, set for instance on hill whole journey is 3 meters, average rate is: (÷ of 3 × 2) (3) =1.5(rice of ÷ of 1+3 of 3 ÷ / second)
22. title has a variety of cases
The title of a lot of types, result often more than one. Classmates must notice watchful careful sex, do the many summary when the problem at ordinary times, consider all cases as far as possible complete. After making a solution, think success.
23. notices watchful integrality
For example, inscribe together so:
Of 3 an internal angle of a triangle than for 1: 1: 2, this is triangle of a ____ .
Do not write into only [isosceles triangle] , right answer should be [isosceles right-angled triangle] . This kind of title, when training at ordinary times only, think more, much summary, guarantee against of the ability when the exam makes a mistake.
The comparison of the area of 24. square and circumference
The area that the square that is 4cm grows by the side of and circumference are unequal! Although numeric result is 16, but differ because of the unit, so 16 square of 16 centimeters of ≠ centimeter, this is cannot relative!
In take an exam at ordinary times in the process that become a problem, must have the habit that think over, accumulate more, much summary, again much title trap also can relaxed get behind!
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