We're dividing 78537797 by 645 
The aim is to understand the frequency of 645 in 78537797.

Moving on to step 1:
The number 645 fits into 7 0 times, leaving a remainder of 7.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
If we subtract 0 from 7, we get 7.
Fetch the next digit (8) from the dividend, attach it to 7 and continue: 78 / 645

On to step 2:
When dividing 78 by 645, we get 0 with a remainder of 78.
Write down 0 as next digit of the result. 
Result so far: 0.0
If we subtract 0 from 78, we get 78.
Include the next digit (5) from the dividend after 78, then repeat: 785 / 645

Going ahead to step 3:
785 divided by 645 is 1 with a remainder of 140.
Record the quotient 1 as the next digit in the result. 
Result so far: 1.0
Subtracting 645 from 785 leaves us with 140.
Bring next digit (3) of the dividend behind the 140 and repeat the process: 1403 / 645

Advancing to step 4:
When dividing 1403 by 645, we get 2 with a remainder of 113.
Record the quotient 2 as the next digit in the result. 
Result so far: 12.0
If we take 1290 away from 1403, we end up with 113.
Bring next digit (7) of the dividend behind the 113 and repeat the process: 1137 / 645

Step 5:
When dividing 1137 by 645, we get 1 with a remainder of 492.
Record the quotient 1 as the next digit in the result. 
Result so far: 121.0
Subtract 645 from 1137 to get 492.
Include the next digit (7) from the dividend after 492, then repeat: 4927 / 645

Advancing to step 6:
645 can be fit into 4927 7 times, resulting in a remainder of 412.
Write down 7 as next digit of the result. 
Result so far: 1217.0
The remainder is 412 after subtracting 4515 from 4927.
Fetch the next digit (9) from the dividend, attach it to 412 and continue: 4129 / 645

Going ahead to step 7:
If we divide 4129 by 645, we get 6 and a remainder of 259.
Use 6 as the next digit of our solution. 
Result so far: 12176.0
The remainder is 259 after subtracting 3870 from 4129.
Append the next digit (7) from the dividend to 259 and continue with: 2597 / 645

Going ahead to step 8:
645 can be fit into 2597 4 times, resulting in a remainder of 17.
Record the quotient 4 as the next digit in the result. 
Result so far: 121764.0
The remainder is 17 after subtracting 2580 from 2597.
Since there are no more digits in the dividend, we add a zero to the remainder making it 170, and continue the process.

Step 9:
If we divide 170 by 645, we get 0 and a remainder of 170.
Put 0 as the next digit of the answer. 
Result so far: 121764.0
Deduct 0 from 170 and we're left with 170.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1700, and continue the process.

Going ahead to step 10:
If we divide 1700 by 645, we get 2 and a remainder of 410.
Use 2 as the next digit of our solution. 
Result so far: 121764.02
Subtract 1290 from 1700 to get 410.
Since there are no more digits in the dividend, we add a zero to the remainder making it 4100, and continue the process.

Advancing to step 11:
When dividing 4100 by 645, we get 6 with a remainder of 230.
Record the quotient 6 as the next digit in the result. 
Result so far: 121764.026
Subtract 3870 from 4100 to get 230.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2300, and continue the process.

Moving on to step 12:
When dividing 2300 by 645, we get 3 with a remainder of 365.
Record the quotient 3 as the next digit in the result. 
Result so far: 121764.0263
If we take 1935 away from 2300, we end up with 365.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3650, and continue the process.

Let's proceed to step 13:
When dividing 3650 by 645, we get 5 with a remainder of 425.
Put 5 as the next digit of the answer. 
Result so far: 121764.02635
If we subtract 3225 from 3650, we get 425.
Since there are no more digits in the dividend, we add a zero to the remainder making it 4250, and continue the process.

Step 14:
When dividing 4250 by 645, we get 6 with a remainder of 380.
Put 6 as the next digit of the answer. 
Result so far: 121764.026356
Subtracting 3870 from 4250 leaves us with 380.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3800, and continue the process.

On to step 15:
If we divide 3800 by 645, we get 5 and a remainder of 575.
Write down 5 as next digit of the result. 
Result so far: 121764.0263565
If we subtract 3225 from 3800, we get 575.
Since there are no more digits in the dividend, we add a zero to the remainder making it 5750, and continue the process.

Going ahead to step 16:
645 goes into 5750 8 times with a remainder of 590.
The next digit of our result is 8. 
Result so far: 121764.02635658
If we take 5160 away from 5750, we end up with 590.
Since there are no more digits in the dividend, we add a zero to the remainder making it 5900, and continue the process.

In conclusion, the division gives 121764.02635658 with a balance of 5.9e-07.