We look at the division of 400121 by 16 
The aim is to understand the frequency of 16 in 400121.

Advancing to step 1:
When dividing 4 by 16, we get 0 with a remainder of 4.
The next digit of our result is 0. 
Result so far: 0.0
Subtract 0 from 4 to get 4.
Fetch the next digit (0) from the dividend, attach it to 4 and continue: 40 / 16

Moving on to step 2:
The number 16 fits into 40 2 times, leaving a remainder of 8.
Record the quotient 2 as the next digit in the result. 
Result so far: 2.0
If we take 32 away from 40, we end up with 8.
Take the next digit (0) from the dividend and append it to 8, then repeat: 80 / 16

Advancing to step 3:
16 goes into 80 5 times with a remainder of 0.
The number 5 becomes the next digit in our result. 
Result so far: 25.0
Subtract 80 from 80 to get 0.
Include the next digit (1) from the dividend after 0, then repeat: 1 / 16

Advancing to step 4:
When dividing 1 by 16, we get 0 with a remainder of 1.
The number 0 becomes the next digit in our result. 
Result so far: 250.0
Deduct 0 from 1 and we're left with 1.
Bring next digit (2) of the dividend behind the 1 and repeat the process: 12 / 16

Moving on to step 5:
16 can be fit into 12 0 times, resulting in a remainder of 12.
The number 0 becomes the next digit in our result. 
Result so far: 2500.0
Subtract 0 from 12 to get 12.
Take the next digit (1) from the dividend and append it to 12, then repeat: 121 / 16

Going ahead to step 6:
16 goes into 121 7 times with a remainder of 9.
The number 7 becomes the next digit in our result. 
Result so far: 25007.0
Subtracting 112 from 121 leaves us with 9.
Since there are no more digits in the dividend, we add a zero to the remainder making it 90, and continue the process.

Going ahead to step 7:
16 goes into 90 5 times with a remainder of 10.
The number 5 becomes the next digit in our result. 
Result so far: 25007.5
Subtracting 80 from 90 leaves us with 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

Going ahead to step 8:
The number 16 fits into 100 6 times, leaving a remainder of 4.
The next digit of our result is 6. 
Result so far: 25007.56
The remainder is 4 after subtracting 96 from 100.
Since there are no more digits in the dividend, we add a zero to the remainder making it 40, and continue the process.

On to step 9:
The number 16 fits into 40 2 times, leaving a remainder of 8.
Put 2 as the next digit of the answer. 
Result so far: 25007.562
Subtract 32 from 40 to get 8.
Since there are no more digits in the dividend, we add a zero to the remainder making it 80, and continue the process.

Advancing to step 10:
16 goes into 80 5 times with a remainder of 0.
Put 5 as the next digit of the answer. 
Result so far: 25007.5625
If we take 80 away from 80, 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.

Moving on to step 11:
The number 16 fits into 0 0 times, leaving a remainder of 0.
Use 0 as the next digit of our solution. 
Result so far: 25007.5625
Subtract 0 from 0 to get 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

Going ahead to step 12:
0 divided by 16 is 0 with a remainder of 0.
Use 0 as the next digit of our solution. 
Result so far: 25007.5625
Deduct 0 from 0 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.

Our division results in 25007.5625 with a remaining 0.0.