Number of copies × number of copies = total number of copies ÷ = total number of copies ÷ = number of copies.
1 multiple× multiple = multiple multiple1multiple = multiple multiple/multiple = 1 multiple
Speed × time = distance/speed = time/distance/time = speed.
Unit price × quantity = total price/total price = total quantity/quantity = unit price.
Work efficiency × working hours = total workload ÷ work efficiency = working hours.
Total workload ÷ working time = working efficiency
Appendix+Appendix = and-one addend = another addend.
Minus-Minus = Difference Minus-Difference = Minus+Minus = Minus
Factor × factor = product ÷ One factor = another factor.
Dividend/Divider = quotient dividend/quotient = divisor quotient × divisor = dividend
Calculation formula of mathematical graphics in primary schools
square
Perimeter area side length
Perimeter = side length ×4 C=4a Area = side length× side length s = a× a.
cube
Volume a: edge length
Surface area = side length × side length× 6 s table =a×a×6 volume = side length× side length× side length.
V=a×a×a
rectangle
Perimeter area side length
Circumference = (length+width) ×2 C=2(a+b)
Area = length × width S=ab
Cubic
V: volume s: area a: length b: width h: height (1) surface area (length× width+length× height+width× height) ×2 S=2(ab+ah+bh).
(2) volume = length× width× height V=abh
triangle
S area a bottom h height area = bottom x height ÷2 s=ah÷2.
Height of triangle = area ×2÷ base of triangle = area ×2÷ height
parallelogram
S area a bottom h height
Area = bottom × height s=ah
trapeziform
Height of upper bottom b and lower bottom h in s area a
Area = (upper bottom+lower bottom) × height ÷2 s=(a+b)× h÷2.
Round; circular
Area c perimeter d= diameter r= radius
(1) perimeter = diameter ×∏=2×∏× radius C=∏ d=2∏r
(2) area = radius × radius×∈
cylinder
V: volume h: height s; Bottom area r: bottom radius c: bottom perimeter
(1) lateral area = bottom perimeter × height (2) surface area = lateral area+bottom area ×2.
(3) Volume = bottom area × height (4) Volume = lateral area ÷2× radius.
cone
V: volume h: height s; Bottom area r: bottom radius
Volume = bottom area × height ÷3 Total number ÷ Total number of copies = average value.
Formula of sum and difference problem
(sum+difference) ÷ 2 = large number (sum-difference) ÷ 2 = decimal.
And folding problems.
Sum ÷ (multiple-1) = decimal × multiple = large number (or sum-decimal = large number)
Difference problem
Difference ÷ (multiple-1) = decimal × multiple = large number (or decimal+difference = large number)
Tree planting problem
1 The problem of planting trees on unclosed lines can be divided into the following three situations:
(1) If trees are planted at both ends of the non-closed line, then:
Number of plants = number of nodes+1 = total length-1.
Total length = plant spacing × (number of plants-1)
Plant spacing = total length ÷ (number of plants-1)
2 If you want to plant trees at one end of the unclosed line and not at the other end, then:
Number of plants = number of segments = total length ÷ plant spacing
Total length = plant spacing × number of plants
Plant spacing = total length/number of plants
(3) If no trees are planted at both ends of the non-closed line, then:
Number of plants = number of nodes-1 = total length-1.
Total length = plant spacing × (number of plants+1)
Plant spacing = total length ÷ (number of plants+1)
The quantitative relationship of planting trees on the closed line is as follows
Number of plants = number of segments = total length ÷ plant spacing
Total length = plant spacing × number of plants
Plant spacing = total length/number of plants
The question of profit and loss
(Profit+Loss) ÷ Difference between two distributions = number of shares participating in distribution.
(Big profit-small profit) ÷ Difference between two distributions = number of shares participating in distribution.
(big loss-small loss) ÷ The difference between two distributions = the number of shares participating in the distribution.
encounter a problem
Meet distance = speed and x meet time = meet distance/sum of speed and speed = meet distance/meet time.
Catch up with the problem
Catch-up distance = speed difference × catch-up time Catch-up time = catch-up distance ÷ speed difference Speed difference = catch-up distance ÷ catch-up time
Tap water problem
Downstream velocity = still water velocity+flow velocity = still water velocity-flow velocity
Still water speed = (downstream speed+countercurrent speed) ÷2 Water flow speed = (downstream speed-countercurrent speed) ÷2
Concentration problem
Solute weight+solvent weight = solution weight/solution weight × 100% = concentration.
Solution weight × concentration = solute weight/solute concentration = solution weight.
Profit and discount problem
Profit = selling price-cost
Profit rate = profit/cost × 100% = (selling price/cost-1) × 100%.
Up and down amount = principal × up and down percentage
Discount = actual selling price ÷ original selling price× 1 00% (discount <1)
Interest = principal × interest rate× time
After-tax interest = principal × interest rate × time × (1-20%)
There are five boxes of apples, and the number of apples in each box is equal. If you take out 18 apples from each box, the remaining apples are exactly equal to the number of apples in the original three boxes. How many apples are there in each box?
* * * Take out: 18× 5 = 90 (only), because the remaining apples are exactly equal to the original 3 boxes of apples, and the apples taken out are exactly 2 (5-3) boxes, so it can be concluded that there are apples in each box: 90 ÷ 2 = 45 (only).