We look at the division of 421723 by 3 
The aim is to understand the frequency of 3 in 421723.

Going ahead to step 1:
3 can be fit into 4 1 times, resulting in a remainder of 1.
The next digit of our result is 1. 
Result so far: 1.0
If we take 3 away from 4, we end up with 1.
Include the next digit (2) from the dividend after 1, then repeat: 12 / 3

Going ahead to step 2:
3 can be fit into 12 4 times, resulting in a remainder of 0.
Put 4 as the next digit of the answer. 
Result so far: 14.0
Deduct 12 from 12 and we're left with 0.
Fetch the next digit (1) from the dividend, attach it to 0 and continue: 1 / 3

Advancing to step 3:
The number 3 fits into 1 0 times, leaving a remainder of 1.
Write down 0 as next digit of the result. 
Result so far: 140.0
If we subtract 0 from 1, we get 1.
Fetch the next digit (7) from the dividend, attach it to 1 and continue: 17 / 3

Moving on to step 4:
3 can be fit into 17 5 times, resulting in a remainder of 2.
Write down 5 as next digit of the result. 
Result so far: 1405.0
Subtracting 15 from 17 leaves us with 2.
Bring next digit (2) of the dividend behind the 2 and repeat the process: 22 / 3

On to step 5:
When dividing 22 by 3, we get 7 with a remainder of 1.
Put 7 as the next digit of the answer. 
Result so far: 14057.0
If we take 21 away from 22, we end up with 1.
Grab the next digit (3) from the dividend, add it to 1, then carry on: 13 / 3

On to step 6:
13 divided by 3 is 4 with a remainder of 1.
Record the quotient 4 as the next digit in the result. 
Result so far: 140574.0
If we subtract 12 from 13, we get 1.
Since there are no more digits in the dividend, we add a zero to the remainder making it 10, and continue the process.

Going ahead to step 7:
3 goes into 10 3 times with a remainder of 1.
Put 3 as the next digit of the answer. 
Result so far: 140574.3
The remainder is 1 after subtracting 9 from 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 10, and continue the process.

On to step 8:
If we divide 10 by 3, we get 3 and a remainder of 1.
Put 3 as the next digit of the answer. 
Result so far: 140574.33
The remainder is 1 after subtracting 9 from 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 10, and continue the process.

In conclusion, the division gives 140574.33 with a balance of 0.001.