791557 ÷ 21 
The aim is to understand the frequency of 21 in 791557.

On to step 1:
21 goes into 7 0 times with a remainder of 7.
Use 0 as the next digit of our solution. 
Result so far: 0.0
Subtracting 0 from 7 leaves us with 7.
Bring next digit (9) of the dividend behind the 7 and repeat the process: 79 / 21

Advancing to step 2:
The number 21 fits into 79 3 times, leaving a remainder of 16.
Use 3 as the next digit of our solution. 
Result so far: 3.0
Deduct 63 from 79 and we're left with 16.
Take the next digit (1) from the dividend and append it to 16, then repeat: 161 / 21

On to step 3:
21 can be fit into 161 7 times, resulting in a remainder of 14.
The number 7 becomes the next digit in our result. 
Result so far: 37.0
Deduct 147 from 161 and we're left with 14.
Append the next digit (5) from the dividend to 14 and continue with: 145 / 21

Moving on to step 4:
21 can be fit into 145 6 times, resulting in a remainder of 19.
Record the quotient 6 as the next digit in the result. 
Result so far: 376.0
Deduct 126 from 145 and we're left with 19.
Bring next digit (5) of the dividend behind the 19 and repeat the process: 195 / 21

Let's proceed to step 5:
The number 21 fits into 195 9 times, leaving a remainder of 6.
The next digit of our result is 9. 
Result so far: 3769.0
If we take 189 away from 195, we end up with 6.
Grab the next digit (7) from the dividend, add it to 6, then carry on: 67 / 21

Advancing to step 6:
The number 21 fits into 67 3 times, leaving a remainder of 4.
Put 3 as the next digit of the answer. 
Result so far: 37693.0
If we subtract 63 from 67, 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.

Going ahead to step 7:
40 divided by 21 is 1 with a remainder of 19.
Put 1 as the next digit of the answer. 
Result so far: 37693.1
The remainder is 19 after subtracting 21 from 40.
Since there are no more digits in the dividend, we add a zero to the remainder making it 190, and continue the process.

On to step 8:
The number 21 fits into 190 9 times, leaving a remainder of 1.
Record the quotient 9 as the next digit in the result. 
Result so far: 37693.19
The remainder is 1 after subtracting 189 from 190.
Since there are no more digits in the dividend, we add a zero to the remainder making it 10, and continue the process.

Advancing to step 9:
The number 21 fits into 10 0 times, leaving a remainder of 10.
The number 0 becomes the next digit in our result. 
Result so far: 37693.19
Subtracting 0 from 10 leaves us 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.

Moving on to step 10:
When dividing 100 by 21, we get 4 with a remainder of 16.
Put 4 as the next digit of the answer. 
Result so far: 37693.1904
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.

On to step 11:
When dividing 160 by 21, we get 7 with a remainder of 13.
Record the quotient 7 as the next digit in the result. 
Result so far: 37693.19047
If we subtract 147 from 160, we get 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.
Write down 6 as next digit of the result. 
Result so far: 37693.190476
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.

On to step 13:
21 goes into 40 1 times with a remainder of 19.
The next digit of our result is 1. 
Result so far: 37693.1904761
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.

On to step 14:
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: 37693.19047619
Subtract 189 from 190 to 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.

The quotient of the division is 37693.19047619, and the remainder is 1e-09.