We look at the division of 913531 by 3 
The aim is to understand the frequency of 3 in 913531.

Let's proceed to step 1:
3 goes into 9 3 times with a remainder of 0.
Record the quotient 3 as the next digit in the result. 
Result so far: 3.0
Subtract 9 from 9 to get 0.
Grab the next digit (1) from the dividend, add it to 0, then carry on: 1 / 3

Going ahead to step 2:
The number 3 fits into 1 0 times, leaving a remainder of 1.
The next digit of our result is 0. 
Result so far: 30.0
Subtract 0 from 1 to get 1.
Bring next digit (3) of the dividend behind the 1 and repeat the process: 13 / 3

Advancing to step 3:
3 goes into 13 4 times with a remainder of 1.
The number 4 becomes the next digit in our result. 
Result so far: 304.0
Subtracting 12 from 13 leaves us with 1.
Fetch the next digit (5) from the dividend, attach it to 1 and continue: 15 / 3

Step 4:
The number 3 fits into 15 5 times, leaving a remainder of 0.
Record the quotient 5 as the next digit in the result. 
Result so far: 3045.0
If we take 15 away from 15, we end up with 0.
Include the next digit (3) from the dividend after 0, then repeat: 3 / 3

Step 5:
If we divide 3 by 3, we get 1 and a remainder of 0.
The next digit of our result is 1. 
Result so far: 30451.0
The remainder is 0 after subtracting 3 from 3.
Append the next digit (1) from the dividend to 0 and continue with: 1 / 3

Step 6:
If we divide 1 by 3, we get 0 and a remainder of 1.
The number 0 becomes the next digit in our result. 
Result so far: 304510.0
Subtracting 0 from 1 leaves us with 1.
Since there are no more digits in the dividend, we add a zero to the remainder making it 10, and continue the process.

Advancing to step 7:
If we divide 10 by 3, we get 3 and a remainder of 1.
Use 3 as the next digit of our solution. 
Result so far: 304510.3
Subtract 9 from 10 to 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.

Step 8:
The number 3 fits into 10 3 times, leaving a remainder of 1.
The number 3 becomes the next digit in our result. 
Result so far: 304510.33
If we take 9 away from 10, we end up with 1.
Since there are no more digits in the dividend, we add a zero to the remainder making it 10, and continue the process.

The final result is 304510.33 with a remainder of 0.001.