37991 ÷ 6 = 6331 R5
Alright, let's work through the division of 37991 by 6 step by step.

Step 1:
6 goes into 3 0 times with a remainder of 3.
Write down 0 as next digit of of the result. 
Result so far: 0
Subtract 0 from 3 to get 3.
Bring next digit (7) of the dividend behind the 3 and repeat the process: 37 / 6

Step 2:
6 goes into 37 6 times with a remainder of 1.
Write down 6 as next digit of of the result. 
Result so far: 6
Subtract 36 from 37 to get 1.
Bring next digit (9) of the dividend behind the 1 and repeat the process: 19 / 6

Step 3:
6 goes into 19 3 times with a remainder of 1.
Write down 3 as next digit of of the result. 
Result so far: 63
Subtract 18 from 19 to get 1.
Bring next digit (9) of the dividend behind the 1 and repeat the process: 19 / 6

Step 4:
6 goes into 19 3 times with a remainder of 1.
Write down 3 as next digit of of the result. 
Result so far: 633
Subtract 18 from 19 to get 1.
Bring next digit (1) of the dividend behind the 1 and repeat the process: 11 / 6

Step 5:
6 goes into 11 1 times with a remainder of 5.
Write down 1 as next digit of of the result. 
Result so far: 6331
Subtract 6 from 11 to get 5.

The final result is 6331 with a remainder of 5.