1991-1988+1985—1982...+17—14+11—8+5—2=()

1991-1988+1985—1982...+17—14+11—8+5—2=()

1991-1988+1985—1982...+17—14+11—8+5—2
=（1991-1988）+（1985—1982）+...+（17—14）+（11—8）+（5—2）
=3+3+3+...+3+3+3
=3×332
=996
In 1991 ~ 2, the tolerance is 3, there are (1991-2) △ 3 + 1 = 664 items, 2 items in each group, there are 664 △ 2 = 332 groups

2000-1997+1994-1991+1988-1985+1982-1972+…… +14-11+8-5+2
I know the answer, but I don't know how 333 came from

（2000-1997）+（1994-1991）+（1998-1995）+（1982-1979）+.+（14-11）+（8-5）+2
=3 + 3 + 3 + 3 + 3 +. + 3 first find several 3: (2000-8) divided by 6 = 332 332 + 1 = 333
Suppose 1994 is the first place, 2000 is the second place, the difference between two numbers is six, the difference between two numbers divided by six is equal to one, 1 + 1 is the number of 2000, and the difference between the first 2000, 1994, 1988 and 1982 in the above formula is six, so (2000-8) divided by 6 = 332 332 + 1 = 333
=3*333+2=999+2=1001

Calculation: 2000-1997 + 1994-1991 + 1988-1985 + 1982-1979 +. + 14-11 + 8-5 + 2

2000-1997=3
1994-1991=3
.
8-5=3
（2000-8）/6=332
So the original formula = 332x3 + 2 = 998

How many hours and minutes is 2.45 hours

It's two hours, 27 minutes