1, square (c: perimeter s: area a: side length)
Perimeter = side length ×4 C=4a
Area = side length × side length S=a×a
2. Cube (V: volume A: side length)
Surface area = side length × side length× ×6 S Table =a×a×6
Volume = side length × side length × side length v = a× a× a.
3. rectangle (c: perimeter s: area a: side length)
Circumference = (length+width) ×2 C=2(a+b)
Area = length × width S=ab
4. Cuboid (V: volume S: area A: length B: width H: height)
(1) surface area (length× width+length× height+width× height )× 2s = 2 (AB+ah+BH)
(2) volume = length× width× height V=abh
5. Triangle (S: area A: base H: height)
Area = bottom × height ÷2 s=ah÷2
Height of triangle = area ×2÷ base of triangle = area ×2÷ height
6. parallelogram (s: area a: bottom h: height)
Area = bottom × height s=ah
7. trapezoid (s: area a: upper bottom b: lower bottom h: height)
Area = (upper bottom+lower bottom) × height ÷2 s=(a+b)× h÷2.
8. Circle (s: area c: perimeter л d= diameter r= radius)
(1) perimeter = diameter× л = 2×л× radius C=лd=2лr
(2) area = radius × radius× л
9. Cylinder (V: volume H: height S: bottom area R: bottom radius C: bottom circumference)
(1) lateral area = bottom perimeter × height =ch(2лr or лd) (2) surface area = lateral area+bottom area ×2.
(3) Volume = bottom area × height (4) Volume = lateral area ÷2× radius.
10, cone (v: volume h: height s: bottom area r: bottom radius)
Volume = bottom area × height ÷3
1 1, total number of copies/total number of copies = average.
12, the formula of sum and difference problem
(sum+difference) ÷ 2 = large number (sum-difference) ÷ 2 = decimal.
13 and the question of time
Sum ÷ (multiple-1) = decimal × multiple = large number (or sum-decimal = large number)
14, differential time problem
Difference ÷ (multiple-1) = decimal × multiple = large number (or decimal+difference = large number)
15, encountered a problem.
Meeting distance = speed × meeting time
Meeting time = meeting distance/speed and
Speed Sum = Meeting Distance/Meeting Time
16, concentration problem
Solute weight+solvent weight = solution weight.
The weight of solute/solution × 100% = concentration.
Solution weight × concentration = solute weight
Solute weight-concentration = solution weight.
17, profit and discount
Profit = selling price-cost
Profit rate = profit/cost × 100% = (selling price/cost-1) × 100%.
Up and down amount = principal × up and down percentage
Interest = principal × interest rate× time
After-tax interest = principal × interest rate × time × (1-20%)
Universal unit conversion
Length unit conversion
1 km =1000m1m =1decimeter/decimeter =10cm1m =10cm/kloc-.
Area unit conversion
1 square kilometer = 100 hectare 1 hectare = 10000 square meter 1 square meter = 100 square decimeter.
1 dm2 = 100 cm2 1 cm2 = 100 mm2
Volume (volume) unit conversion
1 m3 = 1000 cubic decimeter 1 cubic decimeter = 1000 cubic centimeter 1 cubic decimeter = 1 liter.
1 cm3 = 1 ml 1 m3 = 1000 liter
Weight unit conversion
1t = 1000kg 1kg = 1000g 1kg = 1kg。
Rmb unit conversion
1 yuan = 10 angle 1 angle = 10 point 1 yuan = 100 point.
Time unit conversion
1 century = 100 1 year =1February (3 1 day) Yes:1August (30 days) Yes: April and September.
February 28th in a normal year and February 29th in a leap year: 365 days in a normal year and 366 days in a leap year: 1 =24 hours.
1 hour = 60min 1 minute = 60s 1 hour = 3600s.