The first row of 9,7,12,8, the second row of 16,19,20, the third row of 35 spaces, the fourth row of spaces how to find the law

The first row of 9,7,12,8, the second row of 16,19,20, the third row of 35 spaces, the fourth row of spaces how to find the law

9 7 12 8
16 19 20
35 39
seventy-four
9 + 7 = 16; 7 + 12 = 19; 12 + 8 = 20; and so on

The result of expression 3.5 + 1 / 2 + 56% 10 is

3.5+1/2+56%10
3.5+0+6
nine point five

Who can help write a general formula: 6, 12, 30, 90 4,10,24,
Now I urgently need the general formula of these two sequences. If anyone is willing to help me, he will be very grateful!

6,12,30,90……
an=(n+1)(n+2)
=n²+3n+2
4,10,24,56……
an=(n+3)*2^(n-1)

1+2+3+4+5+.
From [1 + 56] + [2 + 55] + [3 + 54] + [4 + 53]
All I know is that every addition is 57
Then, where does 57 * 28 come from
Then we say divide this number by nine to get the remainder
Why divide the number 1596 into [+ 5 + 9 + 6] / 9

As for why the remainder of 1596 divided by 9 is divided into [1 + 5 + 9 + 6] / 9, 1596 = 1000 + 500 + 90 + 61000 divided by 9, 1500 divided by 9, 5, 90 divided by 9, 0 is actually the remainder of 9, 6 divided by 9, 6, so the remainder of 1596 divided by 9 can be divided into (1 + 5 + 9 +)