375094 divided by 21 
The aim is to understand the frequency of 21 in 375094.

Step 1:
When dividing 3 by 21, we get 0 with a remainder of 3.
Use 0 as the next digit of our solution. 
Result so far: 0.0
The remainder is 3 after subtracting 0 from 3.
Take the next digit (7) from the dividend and append it to 3, then repeat: 37 / 21

Moving on to step 2:
21 can be fit into 37 1 times, resulting in a remainder of 16.
Use 1 as the next digit of our solution. 
Result so far: 1.0
Subtracting 21 from 37 leaves us with 16.
Append the next digit (5) from the dividend to 16 and continue with: 165 / 21

Let's proceed to step 3:
The number 21 fits into 165 7 times, leaving a remainder of 18.
Put 7 as the next digit of the answer. 
Result so far: 17.0
The remainder is 18 after subtracting 147 from 165.
Fetch the next digit (0) from the dividend, attach it to 18 and continue: 180 / 21

Going ahead to step 4:
The number 21 fits into 180 8 times, leaving a remainder of 12.
Record the quotient 8 as the next digit in the result. 
Result so far: 178.0
Subtract 168 from 180 to get 12.
Fetch the next digit (9) from the dividend, attach it to 12 and continue: 129 / 21

Advancing to step 5:
21 goes into 129 6 times with a remainder of 3.
The number 6 becomes the next digit in our result. 
Result so far: 1786.0
The remainder is 3 after subtracting 126 from 129.
Append the next digit (4) from the dividend to 3 and continue with: 34 / 21

Moving on to step 6:
When dividing 34 by 21, we get 1 with a remainder of 13.
Put 1 as the next digit of the answer. 
Result so far: 17861.0
Subtracting 21 from 34 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.

Going ahead to step 7:
21 can be fit into 130 6 times, resulting in a remainder of 4.
Write down 6 as next digit of the result. 
Result so far: 17861.6
Deduct 126 from 130 and we're left 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.

Advancing to step 8:
If we divide 40 by 21, we get 1 and a remainder of 19.
Write down 1 as next digit of the result. 
Result so far: 17861.61
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 9:
21 goes into 190 9 times with a remainder of 1.
Use 9 as the next digit of our solution. 
Result so far: 17861.619
Subtracting 189 from 190 leaves us 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.

Step 10:
10 divided by 21 is 0 with a remainder of 10.
Record the quotient 0 as the next digit in the result. 
Result so far: 17861.619
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.

Moving on to step 11:
21 goes into 100 4 times with a remainder of 16.
Put 4 as the next digit of the answer. 
Result so far: 17861.61904
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.

Going ahead to step 12:
When dividing 160 by 21, we get 7 with a remainder of 13.
The number 7 becomes the next digit in our result. 
Result so far: 17861.619047
If we take 147 away from 160, we end up 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.

Moving on to step 13:
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: 17861.6190476
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 14:
21 goes into 40 1 times with a remainder of 19.
Write down 1 as next digit of the result. 
Result so far: 17861.61904761
If we take 21 away from 40, we end up 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.

The final outcome is 17861.61904761, with a leftover of 1.9e-08.