We look at the division of 16286351 by 408 
The aim is to understand the frequency of 408 in 16286351.

Moving on to step 1:
408 goes into 1 0 times with a remainder of 1.
Write down 0 as next digit of the result. 
Result so far: 0.0
The remainder is 1 after subtracting 0 from 1.
Append the next digit (6) from the dividend to 1 and continue with: 16 / 408

Going ahead to step 2:
If we divide 16 by 408, we get 0 and a remainder of 16.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
Subtract 0 from 16 to get 16.
Grab the next digit (2) from the dividend, add it to 16, then carry on: 162 / 408

Step 3:
If we divide 162 by 408, we get 0 and a remainder of 162.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
Subtracting 0 from 162 leaves us with 162.
Grab the next digit (8) from the dividend, add it to 162, then carry on: 1628 / 408

On to step 4:
408 goes into 1628 3 times with a remainder of 404.
Put 3 as the next digit of the answer. 
Result so far: 3.0
If we subtract 1224 from 1628, we get 404.
Take the next digit (6) from the dividend and append it to 404, then repeat: 4046 / 408

Going ahead to step 5:
When dividing 4046 by 408, we get 9 with a remainder of 374.
Use 9 as the next digit of our solution. 
Result so far: 39.0
Deduct 3672 from 4046 and we're left with 374.
Bring next digit (3) of the dividend behind the 374 and repeat the process: 3743 / 408

On to step 6:
408 goes into 3743 9 times with a remainder of 71.
Record the quotient 9 as the next digit in the result. 
Result so far: 399.0
Subtracting 3672 from 3743 leaves us with 71.
Grab the next digit (5) from the dividend, add it to 71, then carry on: 715 / 408

Let's proceed to step 7:
When dividing 715 by 408, we get 1 with a remainder of 307.
Use 1 as the next digit of our solution. 
Result so far: 3991.0
Subtracting 408 from 715 leaves us with 307.
Append the next digit (1) from the dividend to 307 and continue with: 3071 / 408

Let's proceed to step 8:
3071 divided by 408 is 7 with a remainder of 215.
Write down 7 as next digit of the result. 
Result so far: 39917.0
If we subtract 2856 from 3071, we get 215.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2150, and continue the process.

Let's proceed to step 9:
408 can be fit into 2150 5 times, resulting in a remainder of 110.
Use 5 as the next digit of our solution. 
Result so far: 39917.5
Deduct 2040 from 2150 and we're left with 110.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1100, and continue the process.

Going ahead to step 10:
The number 408 fits into 1100 2 times, leaving a remainder of 284.
The number 2 becomes the next digit in our result. 
Result so far: 39917.52
If we subtract 816 from 1100, we get 284.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2840, and continue the process.

Advancing to step 11:
2840 divided by 408 is 6 with a remainder of 392.
The number 6 becomes the next digit in our result. 
Result so far: 39917.526
If we take 2448 away from 2840, we end up with 392.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3920, and continue the process.

Going ahead to step 12:
When dividing 3920 by 408, we get 9 with a remainder of 248.
Use 9 as the next digit of our solution. 
Result so far: 39917.5269
Subtract 3672 from 3920 to get 248.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2480, and continue the process.

Moving on to step 13:
408 goes into 2480 6 times with a remainder of 32.
The number 6 becomes the next digit in our result. 
Result so far: 39917.52696
Subtract 2448 from 2480 to get 32.
Since there are no more digits in the dividend, we add a zero to the remainder making it 320, and continue the process.

Moving on to step 14:
408 goes into 320 0 times with a remainder of 320.
Record the quotient 0 as the next digit in the result. 
Result so far: 39917.52696
The remainder is 320 after subtracting 0 from 320.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3200, and continue the process.

Moving on to step 15:
3200 divided by 408 is 7 with a remainder of 344.
Put 7 as the next digit of the answer. 
Result so far: 39917.5269607
Deduct 2856 from 3200 and we're left with 344.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3440, and continue the process.

On to step 16:
408 goes into 3440 8 times with a remainder of 176.
Write down 8 as next digit of the result. 
Result so far: 39917.52696078
Subtracting 3264 from 3440 leaves us with 176.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1760, and continue the process.

After the division, we end up with 39917.52696078 and a remainder of 1.76e-07.