51915545 ÷ 800 
The aim is to understand the frequency of 800 in 51915545.

Let's proceed to step 1:
The number 800 fits into 5 0 times, leaving a remainder of 5.
The next digit of our result is 0. 
Result so far: 0.0
Subtract 0 from 5 to get 5.
Include the next digit (1) from the dividend after 5, then repeat: 51 / 800

Moving on to step 2:
If we divide 51 by 800, we get 0 and a remainder of 51.
Put 0 as the next digit of the answer. 
Result so far: 0.0
Subtract 0 from 51 to get 51.
Include the next digit (9) from the dividend after 51, then repeat: 519 / 800

Let's proceed to step 3:
The number 800 fits into 519 0 times, leaving a remainder of 519.
Write down 0 as next digit of the result. 
Result so far: 0.0
The remainder is 519 after subtracting 0 from 519.
Take the next digit (1) from the dividend and append it to 519, then repeat: 5191 / 800

Let's proceed to step 4:
800 can be fit into 5191 6 times, resulting in a remainder of 391.
Use 6 as the next digit of our solution. 
Result so far: 6.0
Deduct 4800 from 5191 and we're left with 391.
Take the next digit (5) from the dividend and append it to 391, then repeat: 3915 / 800

Moving on to step 5:
3915 divided by 800 is 4 with a remainder of 715.
Write down 4 as next digit of the result. 
Result so far: 64.0
The remainder is 715 after subtracting 3200 from 3915.
Include the next digit (5) from the dividend after 715, then repeat: 7155 / 800

Going ahead to step 6:
When dividing 7155 by 800, we get 8 with a remainder of 755.
The next digit of our result is 8. 
Result so far: 648.0
Subtracting 6400 from 7155 leaves us with 755.
Bring next digit (4) of the dividend behind the 755 and repeat the process: 7554 / 800

Going ahead to step 7:
7554 divided by 800 is 9 with a remainder of 354.
Record the quotient 9 as the next digit in the result. 
Result so far: 6489.0
Subtract 7200 from 7554 to get 354.
Take the next digit (5) from the dividend and append it to 354, then repeat: 3545 / 800

Moving on to step 8:
800 can be fit into 3545 4 times, resulting in a remainder of 345.
Write down 4 as next digit of the result. 
Result so far: 64894.0
Subtract 3200 from 3545 to get 345.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3450, and continue the process.

Advancing to step 9:
When dividing 3450 by 800, we get 4 with a remainder of 250.
The number 4 becomes the next digit in our result. 
Result so far: 64894.4
Deduct 3200 from 3450 and we're left with 250.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2500, and continue the process.

Advancing to step 10:
When dividing 2500 by 800, we get 3 with a remainder of 100.
The number 3 becomes the next digit in our result. 
Result so far: 64894.43
If we subtract 2400 from 2500, we get 100.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1000, and continue the process.

Moving on to step 11:
800 goes into 1000 1 times with a remainder of 200.
Write down 1 as next digit of the result. 
Result so far: 64894.431
If we subtract 800 from 1000, we get 200.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2000, and continue the process.

On to step 12:
The number 800 fits into 2000 2 times, leaving a remainder of 400.
The number 2 becomes the next digit in our result. 
Result so far: 64894.4312
If we subtract 1600 from 2000, we get 400.
Since there are no more digits in the dividend, we add a zero to the remainder making it 4000, and continue the process.

Going ahead to step 13:
The number 800 fits into 4000 5 times, leaving a remainder of 0.
Put 5 as the next digit of the answer. 
Result so far: 64894.43125
Deduct 4000 from 4000 and we're left with 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

Advancing to step 14:
When dividing 0 by 800, we get 0 with a remainder of 0.
The number 0 becomes the next digit in our result. 
Result so far: 64894.43125
Subtracting 0 from 0 leaves us with 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

Advancing to step 15:
800 goes into 0 0 times with a remainder of 0.
The next digit of our result is 0. 
Result so far: 64894.43125
If we take 0 away from 0, we end up with 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

The final outcome is 64894.43125, with a leftover of 0.0.