1, number of copies × number of copies = total number of copies/number of copies = total number of copies/number of copies = number of copies.

2. 1 multiple× multiple = multiple1multiple = multiple/multiple = 1 multiple

3. Speed × time = distance/speed = time/distance/time = speed

4. Unit price × quantity = total price ÷ unit price = total quantity ÷ quantity = unit price

5. Work efficiency × working hours = total workload ÷ work efficiency = working hours ÷ total workload ÷ working hours = work efficiency.

6. Appendix+Appendix = sum-one addend = another addend

7. Minus-Minus = Minus-Minus = Minus+Minus = Minus

8. Factor × factor = product ÷ one factor = another factor.

9. Dividend = quotient dividend = divisor quotient × divisor = dividend

The circumference of a rectangle = (length+width) ×2 C=(a+b)×2.

Circumference of a square = side length ×4 C=4a

Area of rectangle = length× width S=ab

Area of a square = side length × side length s = a.a = a.

Area of triangle = base × height ÷2 S=ah÷2.

Area of parallelogram = base × height S=ah

Trapezoidal area = (upper bottom+lower bottom) × height ÷2 S=(a+b)h÷2.

Diameter = radius ×2 d=2r Radius = diameter ÷2 r=d÷2.

Circumference = π× diameter = π× radius× 2c = π d = 2π r

Area of circle = π× radius× radius

Area of triangle = base × height ÷2. The formula S=a×h÷2.

Square area = side length × side length formula S=a×a

Area of rectangle = length× width Formula S=a×b

Area of parallelogram = base× height Formula S=a×h

Trapezoidal area = (upper bottom+lower bottom) × height ÷2 Formula S=(a+b)h÷2

Sum of internal angles: sum of internal angles of triangle = 180 degrees.

Cuboid volume = length× width× height formula: V=abh

Volume of cuboid (or cube) = bottom area × height formula: V=abh.

Volume of cube = side length × side length × side length formula: V=aaa.

Circumference = diameter × π formula: L=πd=2πr

Area of circle = radius × radius× π formula: S=πr2.

Transverse area of cylinder: the transverse area of cylinder is equal to the perimeter of bottom multiplied by height. Formula: S=ch=πdh=2πrh.

Surface area of a cylinder: the surface area of a cylinder is equal to the perimeter of the bottom multiplied by the height plus the area of the circles at both ends. Formula: S=ch+2s=ch+2πr2.

Volume of cylinder: the volume of cylinder is equal to the bottom area multiplied by the height. Formula: V=Sh

Volume of cone = 1/3 bottom× product height. Formula: V= 1/3Sh.