251716 ÷ 3 
The aim is to understand the frequency of 3 in 251716.

Advancing to step 1:
The number 3 fits into 2 0 times, leaving a remainder of 2.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
If we take 0 away from 2, we end up with 2.
Append the next digit (5) from the dividend to 2 and continue with: 25 / 3

Going ahead to step 2:
The number 3 fits into 25 8 times, leaving a remainder of 1.
Put 8 as the next digit of the answer. 
Result so far: 8.0
The remainder is 1 after subtracting 24 from 25.
Fetch the next digit (1) from the dividend, attach it to 1 and continue: 11 / 3

Step 3:
If we divide 11 by 3, we get 3 and a remainder of 2.
Use 3 as the next digit of our solution. 
Result so far: 83.0
If we take 9 away from 11, we end up with 2.
Bring next digit (7) of the dividend behind the 2 and repeat the process: 27 / 3

Step 4:
The number 3 fits into 27 9 times, leaving a remainder of 0.
Write down 9 as next digit of the result. 
Result so far: 839.0
Subtracting 27 from 27 leaves us with 0.
Grab the next digit (1) from the dividend, add it to 0, then carry on: 1 / 3

Step 5:
When dividing 1 by 3, we get 0 with a remainder of 1.
The number 0 becomes the next digit in our result. 
Result so far: 8390.0
If we take 0 away from 1, we end up with 1.
Fetch the next digit (6) from the dividend, attach it to 1 and continue: 16 / 3

Advancing to step 6:
3 goes into 16 5 times with a remainder of 1.
Write down 5 as next digit of the result. 
Result so far: 83905.0
Deduct 15 from 16 and we're left 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.

Going ahead to step 7:
10 divided by 3 is 3 with a remainder of 1.
The number 3 becomes the next digit in our result. 
Result so far: 83905.3
Deduct 9 from 10 and we're left 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.

On to step 8:
When dividing 10 by 3, we get 3 with a remainder of 1.
Use 3 as the next digit of our solution. 
Result so far: 83905.33
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.

The final result is 83905.33 with a remainder of 0.001.