84345874 ÷ 521 
The aim is to understand the frequency of 521 in 84345874.

Advancing to step 1:
If we divide 8 by 521, we get 0 and a remainder of 8.
Use 0 as the next digit of our solution. 
Result so far: 0.0
If we subtract 0 from 8, we get 8.
Grab the next digit (4) from the dividend, add it to 8, then carry on: 84 / 521

Step 2:
84 divided by 521 is 0 with a remainder of 84.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
Subtract 0 from 84 to get 84.
Include the next digit (3) from the dividend after 84, then repeat: 843 / 521

Advancing to step 3:
If we divide 843 by 521, we get 1 and a remainder of 322.
The number 1 becomes the next digit in our result. 
Result so far: 1.0
If we take 521 away from 843, we end up with 322.
Include the next digit (4) from the dividend after 322, then repeat: 3224 / 521

Advancing to step 4:
521 can be fit into 3224 6 times, resulting in a remainder of 98.
Put 6 as the next digit of the answer. 
Result so far: 16.0
Subtracting 3126 from 3224 leaves us with 98.
Grab the next digit (5) from the dividend, add it to 98, then carry on: 985 / 521

Let's proceed to step 5:
521 can be fit into 985 1 times, resulting in a remainder of 464.
Use 1 as the next digit of our solution. 
Result so far: 161.0
Subtracting 521 from 985 leaves us with 464.
Bring next digit (8) of the dividend behind the 464 and repeat the process: 4648 / 521

Moving on to step 6:
If we divide 4648 by 521, we get 8 and a remainder of 480.
Put 8 as the next digit of the answer. 
Result so far: 1618.0
Deduct 4168 from 4648 and we're left with 480.
Append the next digit (7) from the dividend to 480 and continue with: 4807 / 521

Step 7:
4807 divided by 521 is 9 with a remainder of 118.
The next digit of our result is 9. 
Result so far: 16189.0
If we take 4689 away from 4807, we end up with 118.
Append the next digit (4) from the dividend to 118 and continue with: 1184 / 521

Moving on to step 8:
The number 521 fits into 1184 2 times, leaving a remainder of 142.
Write down 2 as next digit of the result. 
Result so far: 161892.0
Deduct 1042 from 1184 and we're left with 142.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1420, and continue the process.

On to step 9:
1420 divided by 521 is 2 with a remainder of 378.
The next digit of our result is 2. 
Result so far: 161892.2
Subtracting 1042 from 1420 leaves us with 378.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3780, and continue the process.

On to step 10:
When dividing 3780 by 521, we get 7 with a remainder of 133.
Use 7 as the next digit of our solution. 
Result so far: 161892.27
If we take 3647 away from 3780, we end up with 133.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1330, and continue the process.

Let's proceed to step 11:
When dividing 1330 by 521, we get 2 with a remainder of 288.
Write down 2 as next digit of the result. 
Result so far: 161892.272
The remainder is 288 after subtracting 1042 from 1330.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2880, and continue the process.

Advancing to step 12:
The number 521 fits into 2880 5 times, leaving a remainder of 275.
Put 5 as the next digit of the answer. 
Result so far: 161892.2725
The remainder is 275 after subtracting 2605 from 2880.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2750, and continue the process.

Advancing to step 13:
The number 521 fits into 2750 5 times, leaving a remainder of 145.
Use 5 as the next digit of our solution. 
Result so far: 161892.27255
Deduct 2605 from 2750 and we're left with 145.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1450, and continue the process.

After the division, we end up with 161892.27255 and a remainder of 0.000145.