We're dividing 56415985 by 420 
The aim is to understand the frequency of 420 in 56415985.

Advancing to step 1:
When dividing 5 by 420, we get 0 with a remainder of 5.
Write down 0 as next digit of the result. 
Result so far: 0.0
The remainder is 5 after subtracting 0 from 5.
Bring next digit (6) of the dividend behind the 5 and repeat the process: 56 / 420

Moving on to step 2:
420 can be fit into 56 0 times, resulting in a remainder of 56.
Write down 0 as next digit of the result. 
Result so far: 0.0
If we take 0 away from 56, we end up with 56.
Grab the next digit (4) from the dividend, add it to 56, then carry on: 564 / 420

Going ahead to step 3:
420 goes into 564 1 times with a remainder of 144.
Record the quotient 1 as the next digit in the result. 
Result so far: 1.0
Deduct 420 from 564 and we're left with 144.
Append the next digit (1) from the dividend to 144 and continue with: 1441 / 420

Moving on to step 4:
The number 420 fits into 1441 3 times, leaving a remainder of 181.
The next digit of our result is 3. 
Result so far: 13.0
If we take 1260 away from 1441, we end up with 181.
Take the next digit (5) from the dividend and append it to 181, then repeat: 1815 / 420

Going ahead to step 5:
The number 420 fits into 1815 4 times, leaving a remainder of 135.
Use 4 as the next digit of our solution. 
Result so far: 134.0
Deduct 1680 from 1815 and we're left with 135.
Append the next digit (9) from the dividend to 135 and continue with: 1359 / 420

Let's proceed to step 6:
420 goes into 1359 3 times with a remainder of 99.
Record the quotient 3 as the next digit in the result. 
Result so far: 1343.0
Subtract 1260 from 1359 to get 99.
Append the next digit (8) from the dividend to 99 and continue with: 998 / 420

Going ahead to step 7:
The number 420 fits into 998 2 times, leaving a remainder of 158.
Use 2 as the next digit of our solution. 
Result so far: 13432.0
If we take 840 away from 998, we end up with 158.
Bring next digit (5) of the dividend behind the 158 and repeat the process: 1585 / 420

On to step 8:
If we divide 1585 by 420, we get 3 and a remainder of 325.
Record the quotient 3 as the next digit in the result. 
Result so far: 134323.0
Subtracting 1260 from 1585 leaves us with 325.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3250, and continue the process.

Step 9:
420 can be fit into 3250 7 times, resulting in a remainder of 310.
The next digit of our result is 7. 
Result so far: 134323.7
Deduct 2940 from 3250 and we're left with 310.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3100, and continue the process.

Moving on to step 10:
When dividing 3100 by 420, we get 7 with a remainder of 160.
The number 7 becomes the next digit in our result. 
Result so far: 134323.77
If we take 2940 away from 3100, we end up with 160.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1600, and continue the process.

The final outcome is 134323.77, with a leftover of 0.16.