We divide 63391961 by 4
The aim is to understand the frequency of 4 in 63391961.

Moving on to step 1:
The number 4 fits into 6 1 times, leaving a remainder of 2.
The number 1 becomes the next digit in our result. 
Result so far: 1.0
If we subtract 4 from 6, we get 2.
Fetch the next digit (3) from the dividend, attach it to 2 and continue: 23 / 4

Moving on to step 2:
23 divided by 4 is 5 with a remainder of 3.
Write down 5 as next digit of the result. 
Result so far: 15.0
Subtract 20 from 23 to get 3.
Bring next digit (3) of the dividend behind the 3 and repeat the process: 33 / 4

Let's proceed to step 3:
If we divide 33 by 4, we get 8 and a remainder of 1.
The number 8 becomes the next digit in our result. 
Result so far: 158.0
Subtract 32 from 33 to get 1.
Fetch the next digit (9) from the dividend, attach it to 1 and continue: 19 / 4

Moving on to step 4:
4 goes into 19 4 times with a remainder of 3.
Put 4 as the next digit of the answer. 
Result so far: 1584.0
Deduct 16 from 19 and we're left with 3.
Fetch the next digit (1) from the dividend, attach it to 3 and continue: 31 / 4

Step 5:
31 divided by 4 is 7 with a remainder of 3.
Write down 7 as next digit of the result. 
Result so far: 15847.0
The remainder is 3 after subtracting 28 from 31.
Append the next digit (9) from the dividend to 3 and continue with: 39 / 4

Step 6:
When dividing 39 by 4, we get 9 with a remainder of 3.
Record the quotient 9 as the next digit in the result. 
Result so far: 158479.0
If we take 36 away from 39, we end up with 3.
Append the next digit (6) from the dividend to 3 and continue with: 36 / 4

Advancing to step 7:
If we divide 36 by 4, we get 9 and a remainder of 0.
The number 9 becomes the next digit in our result. 
Result so far: 1584799.0
Subtract 36 from 36 to get 0.
Take the next digit (1) from the dividend and append it to 0, then repeat: 1 / 4

Let's proceed to step 8:
When dividing 1 by 4, we get 0 with a remainder of 1.
Put 0 as the next digit of the answer. 
Result so far: 15847990.0
If we subtract 0 from 1, we 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.

Going ahead to step 9:
The number 4 fits into 10 2 times, leaving a remainder of 2.
The next digit of our result is 2. 
Result so far: 15847990.2
Subtract 8 from 10 to get 2.
Since there are no more digits in the dividend, we add a zero to the remainder making it 20, and continue the process.

Let's proceed to step 10:
4 goes into 20 5 times with a remainder of 0.
The number 5 becomes the next digit in our result. 
Result so far: 15847990.25
Deduct 20 from 20 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.

Moving on to step 11:
When dividing 0 by 4, we get 0 with a remainder of 0.
Use 0 as the next digit of our solution. 
Result so far: 15847990.25
The remainder is 0 after subtracting 0 from 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 12:
4 can be fit into 0 0 times, resulting in a remainder of 0.
The next digit of our result is 0. 
Result so far: 15847990.25
The remainder is 0 after subtracting 0 from 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 result is 15847990.25 with a remainder of 0.0.