378877 divided by 21 
We want to figure out the number of times 378877 can be divided by 21.

Advancing to step 1:
21 goes into 3 0 times with a remainder of 3.
Put 0 as the next digit of the answer. 
Result so far: 0.0
If we subtract 0 from 3, we get 3.
Bring next digit (7) of the dividend behind the 3 and repeat the process: 37 / 21

Advancing to step 2:
21 can be fit into 37 1 times, resulting in a remainder of 16.
Record the quotient 1 as the next digit in the result. 
Result so far: 1.0
Deduct 21 from 37 and we're left with 16.
Take the next digit (8) from the dividend and append it to 16, then repeat: 168 / 21

Step 3:
21 can be fit into 168 8 times, resulting in a remainder of 0.
Put 8 as the next digit of the answer. 
Result so far: 18.0
The remainder is 0 after subtracting 168 from 168.
Bring next digit (8) of the dividend behind the 0 and repeat the process: 8 / 21

Let's proceed to step 4:
21 goes into 8 0 times with a remainder of 8.
The number 0 becomes the next digit in our result. 
Result so far: 180.0
Deduct 0 from 8 and we're left with 8.
Take the next digit (7) from the dividend and append it to 8, then repeat: 87 / 21

Going ahead to step 5:
The number 21 fits into 87 4 times, leaving a remainder of 3.
Record the quotient 4 as the next digit in the result. 
Result so far: 1804.0
Subtract 84 from 87 to get 3.
Take the next digit (7) from the dividend and append it to 3, then repeat: 37 / 21

Advancing to step 6:
37 divided by 21 is 1 with a remainder of 16.
Put 1 as the next digit of the answer. 
Result so far: 18041.0
Subtract 21 from 37 to get 16.
Since there are no more digits in the dividend, we add a zero to the remainder making it 160, and continue the process.

Advancing to step 7:
21 can be fit into 160 7 times, resulting in a remainder of 13.
Use 7 as the next digit of our solution. 
Result so far: 18041.7
Deduct 147 from 160 and we're left with 13.
Since there are no more digits in the dividend, we add a zero to the remainder making it 130, and continue the process.

Step 8:
21 can be fit into 130 6 times, resulting in a remainder of 4.
Use 6 as the next digit of our solution. 
Result so far: 18041.76
If we subtract 126 from 130, we get 4.
Since there are no more digits in the dividend, we add a zero to the remainder making it 40, and continue the process.

On to step 9:
40 divided by 21 is 1 with a remainder of 19.
Write down 1 as next digit of the result. 
Result so far: 18041.761
Deduct 21 from 40 and we're left with 19.
Since there are no more digits in the dividend, we add a zero to the remainder making it 190, and continue the process.

Step 10:
When dividing 190 by 21, we get 9 with a remainder of 1.
Use 9 as the next digit of our solution. 
Result so far: 18041.7619
If we subtract 189 from 190, we get 1.
Since there are no more digits in the dividend, we add a zero to the remainder making it 10, and continue the process.

Moving on to step 11:
When dividing 10 by 21, we get 0 with a remainder of 10.
Use 0 as the next digit of our solution. 
Result so far: 18041.7619
Deduct 0 from 10 and we're left with 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

Step 12:
When dividing 100 by 21, we get 4 with a remainder of 16.
Write down 4 as next digit of the result. 
Result so far: 18041.761904
Deduct 84 from 100 and we're left with 16.
Since there are no more digits in the dividend, we add a zero to the remainder making it 160, and continue the process.

Moving on to step 13:
The number 21 fits into 160 7 times, leaving a remainder of 13.
Use 7 as the next digit of our solution. 
Result so far: 18041.7619047
Deduct 147 from 160 and we're left with 13.
Since there are no more digits in the dividend, we add a zero to the remainder making it 130, and continue the process.

Advancing to step 14:
21 goes into 130 6 times with a remainder of 4.
Record the quotient 6 as the next digit in the result. 
Result so far: 18041.76190476
If we take 126 away from 130, we end up with 4.
Since there are no more digits in the dividend, we add a zero to the remainder making it 40, and continue the process.

Our division results in 18041.76190476 with a remaining 4e-09.