16890108 ÷ 420 
The aim is to understand the frequency of 420 in 16890108.

Advancing to step 1:
If we divide 1 by 420, we get 0 and a remainder of 1.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
If we subtract 0 from 1, we get 1.
Grab the next digit (6) from the dividend, add it to 1, then carry on: 16 / 420

Going ahead to step 2:
The number 420 fits into 16 0 times, leaving a remainder of 16.
Put 0 as the next digit of the answer. 
Result so far: 0.0
The remainder is 16 after subtracting 0 from 16.
Fetch the next digit (8) from the dividend, attach it to 16 and continue: 168 / 420

Let's proceed to step 3:
When dividing 168 by 420, we get 0 with a remainder of 168.
Put 0 as the next digit of the answer. 
Result so far: 0.0
If we subtract 0 from 168, we get 168.
Append the next digit (9) from the dividend to 168 and continue with: 1689 / 420

Let's proceed to step 4:
420 can be fit into 1689 4 times, resulting in a remainder of 9.
Put 4 as the next digit of the answer. 
Result so far: 4.0
The remainder is 9 after subtracting 1680 from 1689.
Fetch the next digit (0) from the dividend, attach it to 9 and continue: 90 / 420

On to step 5:
90 divided by 420 is 0 with a remainder of 90.
Use 0 as the next digit of our solution. 
Result so far: 40.0
Subtracting 0 from 90 leaves us with 90.
Grab the next digit (1) from the dividend, add it to 90, then carry on: 901 / 420

Let's proceed to step 6:
901 divided by 420 is 2 with a remainder of 61.
The number 2 becomes the next digit in our result. 
Result so far: 402.0
If we subtract 840 from 901, we get 61.
Take the next digit (0) from the dividend and append it to 61, then repeat: 610 / 420

Moving on to step 7:
The number 420 fits into 610 1 times, leaving a remainder of 190.
Write down 1 as next digit of the result. 
Result so far: 4021.0
If we subtract 420 from 610, we get 190.
Take the next digit (8) from the dividend and append it to 190, then repeat: 1908 / 420

Let's proceed to step 8:
When dividing 1908 by 420, we get 4 with a remainder of 228.
Write down 4 as next digit of the result. 
Result so far: 40214.0
Subtract 1680 from 1908 to get 228.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2280, and continue the process.

Moving on to step 9:
420 goes into 2280 5 times with a remainder of 180.
The number 5 becomes the next digit in our result. 
Result so far: 40214.5
Subtracting 2100 from 2280 leaves us with 180.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1800, and continue the process.

Step 10:
1800 divided by 420 is 4 with a remainder of 120.
Use 4 as the next digit of our solution. 
Result so far: 40214.54
Deduct 1680 from 1800 and we're left with 120.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1200, and continue the process.

Going ahead to step 11:
The number 420 fits into 1200 2 times, leaving a remainder of 360.
The number 2 becomes the next digit in our result. 
Result so far: 40214.542
Subtract 840 from 1200 to get 360.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3600, and continue the process.

Let's proceed to step 12:
The number 420 fits into 3600 8 times, leaving a remainder of 240.
The number 8 becomes the next digit in our result. 
Result so far: 40214.5428
If we subtract 3360 from 3600, we get 240.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2400, and continue the process.

Moving on to step 13:
2400 divided by 420 is 5 with a remainder of 300.
The next digit of our result is 5. 
Result so far: 40214.54285
Subtract 2100 from 2400 to get 300.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3000, and continue the process.

Moving on to step 14:
If we divide 3000 by 420, we get 7 and a remainder of 60.
The number 7 becomes the next digit in our result. 
Result so far: 40214.542857
If we take 2940 away from 3000, we end up with 60.
Since there are no more digits in the dividend, we add a zero to the remainder making it 600, and continue the process.

Step 15:
420 can be fit into 600 1 times, resulting in a remainder of 180.
Record the quotient 1 as the next digit in the result. 
Result so far: 40214.5428571
Subtract 420 from 600 to get 180.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1800, and continue the process.

Moving on to step 16:
1800 divided by 420 is 4 with a remainder of 120.
Record the quotient 4 as the next digit in the result. 
Result so far: 40214.54285714
If we take 1680 away from 1800, we end up with 120.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1200, and continue the process.

After the division, we end up with 40214.54285714 and a remainder of 1.2e-07.