Find the rule to fill in the number 2÷7=0.285714285714… 3÷7=0.428571428571… 4÷7=5÷7=6÷7=8÷7=

Find the rule to fill in the number 2÷7=0.285714285714… 3÷7=0.428571428571… 4÷7=5÷7=6÷7=8÷7=

1÷7=0.142857142857… 2÷7=0.285714285714… 3÷7=0.428571428571… 4÷7=0.571428571428… 5÷7=0.714285714285… 6÷7=0.857142857142… 8÷7=1.142857142857…

Find the law of formula
1×2+2×3+···+n（n+1）=?
Look at the following three equations:
1×2=1/3(1×2×3-0×1×2)
2×3=1/3(2×3×4-1×2×3)
3×4=1/3(3×4×5-2×3×4)
By adding the two sides of the three equations, we can get 1 × 2 + 2 × 3 + 3 × 4 = 1 / 3 × 3 × 4 × 5 = 20
After reading this passage, please think about it and answer:
(1)1×2+2×3+···+9×10=____________________________
(2)1×2×3+2×3×4+···+9×10×11=_____________________________
(3)1×2×3+2×3×4+···+n×（n+1）×（n+2)=_______________________
There should be two parts and one result on the horizontal line
Example: 1 × 2 + 2 × 3 + 3 × 4 = (1 / 3 × 3 × 4 × 5 = 20)
In parentheses is the format on the line

(1)1×2+2×3+···+9×10=__ 1/3*9*10*11=330__________________________
(2)1×2×3+2×3×4+···+9×10×11=__ 1/4*9*10*11*12=2970___________________________
(3)1×2×3+2×3×4+···+n×（n+1）×（n+2)=_ 1/4*n*(n+1)*(n+2)*(n+3)______________________