83774478 divided by 645 
The aim is to understand the frequency of 645 in 83774478.

Step 1:
If we divide 8 by 645, we get 0 and a remainder of 8.
Write down 0 as next digit of the result. 
Result so far: 0.0
The remainder is 8 after subtracting 0 from 8.
Fetch the next digit (3) from the dividend, attach it to 8 and continue: 83 / 645

On to step 2:
645 can be fit into 83 0 times, resulting in a remainder of 83.
The next digit of our result is 0. 
Result so far: 0.0
Subtracting 0 from 83 leaves us with 83.
Append the next digit (7) from the dividend to 83 and continue with: 837 / 645

On to step 3:
645 can be fit into 837 1 times, resulting in a remainder of 192.
The number 1 becomes the next digit in our result. 
Result so far: 1.0
Subtracting 645 from 837 leaves us with 192.
Fetch the next digit (7) from the dividend, attach it to 192 and continue: 1927 / 645

Going ahead to step 4:
If we divide 1927 by 645, we get 2 and a remainder of 637.
The number 2 becomes the next digit in our result. 
Result so far: 12.0
The remainder is 637 after subtracting 1290 from 1927.
Grab the next digit (4) from the dividend, add it to 637, then carry on: 6374 / 645

Advancing to step 5:
645 goes into 6374 9 times with a remainder of 569.
Write down 9 as next digit of the result. 
Result so far: 129.0
Deduct 5805 from 6374 and we're left with 569.
Take the next digit (4) from the dividend and append it to 569, then repeat: 5694 / 645

Advancing to step 6:
The number 645 fits into 5694 8 times, leaving a remainder of 534.
The next digit of our result is 8. 
Result so far: 1298.0
Subtract 5160 from 5694 to get 534.
Append the next digit (7) from the dividend to 534 and continue with: 5347 / 645

Step 7:
5347 divided by 645 is 8 with a remainder of 187.
Record the quotient 8 as the next digit in the result. 
Result so far: 12988.0
The remainder is 187 after subtracting 5160 from 5347.
Take the next digit (8) from the dividend and append it to 187, then repeat: 1878 / 645

Moving on to step 8:
1878 divided by 645 is 2 with a remainder of 588.
Record the quotient 2 as the next digit in the result. 
Result so far: 129882.0
If we take 1290 away from 1878, we end up with 588.
Since there are no more digits in the dividend, we add a zero to the remainder making it 5880, and continue the process.

Let's proceed to step 9:
645 goes into 5880 9 times with a remainder of 75.
The number 9 becomes the next digit in our result. 
Result so far: 129882.9
If we take 5805 away from 5880, we end up with 75.
Since there are no more digits in the dividend, we add a zero to the remainder making it 750, and continue the process.

Moving on to step 10:
750 divided by 645 is 1 with a remainder of 105.
Put 1 as the next digit of the answer. 
Result so far: 129882.91
Deduct 645 from 750 and we're left with 105.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1050, and continue the process.

Moving on to step 11:
645 can be fit into 1050 1 times, resulting in a remainder of 405.
Put 1 as the next digit of the answer. 
Result so far: 129882.911
Subtract 645 from 1050 to get 405.
Since there are no more digits in the dividend, we add a zero to the remainder making it 4050, and continue the process.

Our division results in 129882.911 with a remaining 0.0405.