721807 divided by 42 
The aim is to understand the frequency of 42 in 721807.

On to step 1:
If we divide 7 by 42, we get 0 and a remainder of 7.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
The remainder is 7 after subtracting 0 from 7.
Grab the next digit (2) from the dividend, add it to 7, then carry on: 72 / 42

Moving on to step 2:
When dividing 72 by 42, we get 1 with a remainder of 30.
Record the quotient 1 as the next digit in the result. 
Result so far: 1.0
Subtract 42 from 72 to get 30.
Fetch the next digit (1) from the dividend, attach it to 30 and continue: 301 / 42

Going ahead to step 3:
42 goes into 301 7 times with a remainder of 7.
Write down 7 as next digit of the result. 
Result so far: 17.0
If we take 294 away from 301, we end up with 7.
Append the next digit (8) from the dividend to 7 and continue with: 78 / 42

On to step 4:
The number 42 fits into 78 1 times, leaving a remainder of 36.
The number 1 becomes the next digit in our result. 
Result so far: 171.0
Deduct 42 from 78 and we're left with 36.
Include the next digit (0) from the dividend after 36, then repeat: 360 / 42

Advancing to step 5:
42 can be fit into 360 8 times, resulting in a remainder of 24.
The number 8 becomes the next digit in our result. 
Result so far: 1718.0
If we subtract 336 from 360, we get 24.
Take the next digit (7) from the dividend and append it to 24, then repeat: 247 / 42

Let's proceed to step 6:
When dividing 247 by 42, we get 5 with a remainder of 37.
Put 5 as the next digit of the answer. 
Result so far: 17185.0
If we subtract 210 from 247, we get 37.
Since there are no more digits in the dividend, we add a zero to the remainder making it 370, and continue the process.

Let's proceed to step 7:
When dividing 370 by 42, we get 8 with a remainder of 34.
Use 8 as the next digit of our solution. 
Result so far: 17185.8
If we subtract 336 from 370, we get 34.
Since there are no more digits in the dividend, we add a zero to the remainder making it 340, and continue the process.

Advancing to step 8:
The number 42 fits into 340 8 times, leaving a remainder of 4.
Put 8 as the next digit of the answer. 
Result so far: 17185.88
Subtract 336 from 340 to get 4.
Since there are no more digits in the dividend, we add a zero to the remainder making it 40, and continue the process.

After the division, we end up with 17185.88 and a remainder of 0.004.