We look at the division of 648636 by 7 
The aim is to understand the frequency of 7 in 648636.

On to step 1:
The number 7 fits into 6 0 times, leaving a remainder of 6.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
If we take 0 away from 6, we end up with 6.
Include the next digit (4) from the dividend after 6, then repeat: 64 / 7

Let's proceed to step 2:
7 goes into 64 9 times with a remainder of 1.
Put 9 as the next digit of the answer. 
Result so far: 9.0
Subtracting 63 from 64 leaves us with 1.
Append the next digit (8) from the dividend to 1 and continue with: 18 / 7

Moving on to step 3:
The number 7 fits into 18 2 times, leaving a remainder of 4.
Record the quotient 2 as the next digit in the result. 
Result so far: 92.0
If we subtract 14 from 18, we get 4.
Bring next digit (6) of the dividend behind the 4 and repeat the process: 46 / 7

Advancing to step 4:
7 goes into 46 6 times with a remainder of 4.
Put 6 as the next digit of the answer. 
Result so far: 926.0
If we subtract 42 from 46, we get 4.
Grab the next digit (3) from the dividend, add it to 4, then carry on: 43 / 7

Step 5:
7 can be fit into 43 6 times, resulting in a remainder of 1.
The next digit of our result is 6. 
Result so far: 9266.0
If we take 42 away from 43, we end up with 1.
Append the next digit (6) from the dividend to 1 and continue with: 16 / 7

Step 6:
The number 7 fits into 16 2 times, leaving a remainder of 2.
Put 2 as the next digit of the answer. 
Result so far: 92662.0
Subtracting 14 from 16 leaves us with 2.
Since there are no more digits in the dividend, we add a zero to the remainder making it 20, and continue the process.

Moving on to step 7:
If we divide 20 by 7, we get 2 and a remainder of 6.
The next digit of our result is 2. 
Result so far: 92662.2
Deduct 14 from 20 and we're left with 6.
Since there are no more digits in the dividend, we add a zero to the remainder making it 60, and continue the process.

Advancing to step 8:
60 divided by 7 is 8 with a remainder of 4.
Write down 8 as next digit of the result. 
Result so far: 92662.28
If we subtract 56 from 60, we get 4.
Since there are no more digits in the dividend, we add a zero to the remainder making it 40, and continue the process.

Advancing to step 9:
When dividing 40 by 7, we get 5 with a remainder of 5.
Record the quotient 5 as the next digit in the result. 
Result so far: 92662.285
Subtracting 35 from 40 leaves us with 5.
Since there are no more digits in the dividend, we add a zero to the remainder making it 50, and continue the process.

Let's proceed to step 10:
The number 7 fits into 50 7 times, leaving a remainder of 1.
Record the quotient 7 as the next digit in the result. 
Result so far: 92662.2857
Subtract 49 from 50 to get 1.
Since there are no more digits in the dividend, we add a zero to the remainder making it 10, and continue the process.

Step 11:
The number 7 fits into 10 1 times, leaving a remainder of 3.
Put 1 as the next digit of the answer. 
Result so far: 92662.28571
Deduct 7 from 10 and we're left with 3.
Since there are no more digits in the dividend, we add a zero to the remainder making it 30, and continue the process.

Let's proceed to step 12:
7 goes into 30 4 times with a remainder of 2.
Put 4 as the next digit of the answer. 
Result so far: 92662.285714
If we take 28 away from 30, we end up with 2.
Since there are no more digits in the dividend, we add a zero to the remainder making it 20, and continue the process.

Going ahead to step 13:
The number 7 fits into 20 2 times, leaving a remainder of 6.
Put 2 as the next digit of the answer. 
Result so far: 92662.2857142
The remainder is 6 after subtracting 14 from 20.
Since there are no more digits in the dividend, we add a zero to the remainder making it 60, and continue the process.

Let's proceed to step 14:
60 divided by 7 is 8 with a remainder of 4.
Record the quotient 8 as the next digit in the result. 
Result so far: 92662.28571428
The remainder is 4 after subtracting 56 from 60.
Since there are no more digits in the dividend, we add a zero to the remainder making it 40, and continue the process.

The final outcome is 92662.28571428, with a leftover of 4e-09.