51148 divided by 21 
The aim is to understand the frequency of 21 in 51148.

Moving on to step 1:
When dividing 5 by 21, we get 0 with a remainder of 5.
Write down 0 as next digit of the result. 
Result so far: 0.0
The remainder is 5 after subtracting 0 from 5.
Grab the next digit (1) from the dividend, add it to 5, then carry on: 51 / 21

Going ahead to step 2:
The number 21 fits into 51 2 times, leaving a remainder of 9.
Put 2 as the next digit of the answer. 
Result so far: 2.0
Subtracting 42 from 51 leaves us with 9.
Take the next digit (1) from the dividend and append it to 9, then repeat: 91 / 21

Advancing to step 3:
The number 21 fits into 91 4 times, leaving a remainder of 7.
Record the quotient 4 as the next digit in the result. 
Result so far: 24.0
If we subtract 84 from 91, we get 7.
Grab the next digit (4) from the dividend, add it to 7, then carry on: 74 / 21

Going ahead to step 4:
If we divide 74 by 21, we get 3 and a remainder of 11.
The number 3 becomes the next digit in our result. 
Result so far: 243.0
The remainder is 11 after subtracting 63 from 74.
Take the next digit (8) from the dividend and append it to 11, then repeat: 118 / 21

Let's proceed to step 5:
The number 21 fits into 118 5 times, leaving a remainder of 13.
Use 5 as the next digit of our solution. 
Result so far: 2435.0
The remainder is 13 after subtracting 105 from 118.
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 6:
21 can be fit into 130 6 times, resulting in a remainder of 4.
The number 6 becomes the next digit in our result. 
Result so far: 2435.6
The remainder is 4 after subtracting 126 from 130.
Since there are no more digits in the dividend, we add a zero to the remainder making it 40, and continue the process.

Let's proceed to step 7:
40 divided by 21 is 1 with a remainder of 19.
The number 1 becomes the next digit in our result. 
Result so far: 2435.61
Subtract 21 from 40 to get 19.
Since there are no more digits in the dividend, we add a zero to the remainder making it 190, and continue the process.

Going ahead to step 8:
If we divide 190 by 21, we get 9 and a remainder of 1.
Put 9 as the next digit of the answer. 
Result so far: 2435.619
Deduct 189 from 190 and we're left with 1.
Since there are no more digits in the dividend, we add a zero to the remainder making it 10, and continue the process.

On to step 9:
10 divided by 21 is 0 with a remainder of 10.
Write down 0 as next digit of the result. 
Result so far: 2435.619
Subtract 0 from 10 to get 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

Advancing to step 10:
If we divide 100 by 21, we get 4 and a remainder of 16.
Record the quotient 4 as the next digit in the result. 
Result so far: 2435.61904
Subtracting 84 from 100 leaves us 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 11:
If we divide 160 by 21, we get 7 and a remainder of 13.
Record the quotient 7 as the next digit in the result. 
Result so far: 2435.619047
Subtracting 147 from 160 leaves us 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.

Let's proceed to step 12:
When dividing 130 by 21, we get 6 with a remainder of 4.
Record the quotient 6 as the next digit in the result. 
Result so far: 2435.6190476
Subtract 126 from 130 to 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.

Step 13:
When dividing 40 by 21, we get 1 with a remainder of 19.
Use 1 as the next digit of our solution. 
Result so far: 2435.61904761
If we subtract 21 from 40, we get 19.
Since there are no more digits in the dividend, we add a zero to the remainder making it 190, and continue the process.

The quotient of the division is 2435.61904761, and the remainder is 1.9e-08.