66571594 ÷ 258 
The aim is to understand the frequency of 258 in 66571594.

Step 1:
If we divide 6 by 258, we get 0 and a remainder of 6.
Write down 0 as next digit of the result. 
Result so far: 0.0
If we subtract 0 from 6, we get 6.
Take the next digit (6) from the dividend and append it to 6, then repeat: 66 / 258

Going ahead to step 2:
When dividing 66 by 258, we get 0 with a remainder of 66.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
Subtracting 0 from 66 leaves us with 66.
Take the next digit (5) from the dividend and append it to 66, then repeat: 665 / 258

On to step 3:
665 divided by 258 is 2 with a remainder of 149.
The number 2 becomes the next digit in our result. 
Result so far: 2.0
The remainder is 149 after subtracting 516 from 665.
Append the next digit (7) from the dividend to 149 and continue with: 1497 / 258

Step 4:
1497 divided by 258 is 5 with a remainder of 207.
Use 5 as the next digit of our solution. 
Result so far: 25.0
If we subtract 1290 from 1497, we get 207.
Fetch the next digit (1) from the dividend, attach it to 207 and continue: 2071 / 258

Step 5:
258 goes into 2071 8 times with a remainder of 7.
Use 8 as the next digit of our solution. 
Result so far: 258.0
Deduct 2064 from 2071 and we're left with 7.
Take the next digit (5) from the dividend and append it to 7, then repeat: 75 / 258

On to step 6:
When dividing 75 by 258, we get 0 with a remainder of 75.
Record the quotient 0 as the next digit in the result. 
Result so far: 2580.0
Subtract 0 from 75 to get 75.
Bring next digit (9) of the dividend behind the 75 and repeat the process: 759 / 258

Step 7:
258 can be fit into 759 2 times, resulting in a remainder of 243.
Write down 2 as next digit of the result. 
Result so far: 25802.0
If we subtract 516 from 759, we get 243.
Take the next digit (4) from the dividend and append it to 243, then repeat: 2434 / 258

Moving on to step 8:
If we divide 2434 by 258, we get 9 and a remainder of 112.
The next digit of our result is 9. 
Result so far: 258029.0
Subtract 2322 from 2434 to get 112.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1120, and continue the process.

Moving on to step 9:
258 goes into 1120 4 times with a remainder of 88.
Write down 4 as next digit of the result. 
Result so far: 258029.4
Deduct 1032 from 1120 and we're left with 88.
Since there are no more digits in the dividend, we add a zero to the remainder making it 880, and continue the process.

Advancing to step 10:
If we divide 880 by 258, we get 3 and a remainder of 106.
Put 3 as the next digit of the answer. 
Result so far: 258029.43
Subtract 774 from 880 to get 106.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1060, and continue the process.

On to step 11:
If we divide 1060 by 258, we get 4 and a remainder of 28.
Record the quotient 4 as the next digit in the result. 
Result so far: 258029.434
If we subtract 1032 from 1060, we get 28.
Since there are no more digits in the dividend, we add a zero to the remainder making it 280, and continue the process.

Going ahead to step 12:
When dividing 280 by 258, we get 1 with a remainder of 22.
Write down 1 as next digit of the result. 
Result so far: 258029.4341
If we take 258 away from 280, we end up with 22.
Since there are no more digits in the dividend, we add a zero to the remainder making it 220, and continue the process.

Let's proceed to step 13:
258 goes into 220 0 times with a remainder of 220.
Put 0 as the next digit of the answer. 
Result so far: 258029.4341
If we take 0 away from 220, we end up with 220.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2200, and continue the process.

Advancing to step 14:
When dividing 2200 by 258, we get 8 with a remainder of 136.
The next digit of our result is 8. 
Result so far: 258029.434108
If we subtract 2064 from 2200, we get 136.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1360, and continue the process.

Moving on to step 15:
1360 divided by 258 is 5 with a remainder of 70.
The next digit of our result is 5. 
Result so far: 258029.4341085
If we take 1290 away from 1360, we end up with 70.
Since there are no more digits in the dividend, we add a zero to the remainder making it 700, and continue the process.

Moving on to step 16:
258 goes into 700 2 times with a remainder of 184.
Put 2 as the next digit of the answer. 
Result so far: 258029.43410852
Deduct 516 from 700 and we're left with 184.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1840, and continue the process.

In conclusion, the division gives 258029.43410852 with a balance of 1.84e-07.