We look at the division of 3986357 by 840 
The aim is to understand the frequency of 840 in 3986357.

Step 1:
The number 840 fits into 3 0 times, leaving a remainder of 3.
Use 0 as the next digit of our solution. 
Result so far: 0.0
Deduct 0 from 3 and we're left with 3.
Bring next digit (9) of the dividend behind the 3 and repeat the process: 39 / 840

Let's proceed to step 2:
If we divide 39 by 840, we get 0 and a remainder of 39.
Put 0 as the next digit of the answer. 
Result so far: 0.0
Subtracting 0 from 39 leaves us with 39.
Bring next digit (8) of the dividend behind the 39 and repeat the process: 398 / 840

Moving on to step 3:
The number 840 fits into 398 0 times, leaving a remainder of 398.
Put 0 as the next digit of the answer. 
Result so far: 0.0
Subtracting 0 from 398 leaves us with 398.
Include the next digit (6) from the dividend after 398, then repeat: 3986 / 840

Going ahead to step 4:
When dividing 3986 by 840, we get 4 with a remainder of 626.
Record the quotient 4 as the next digit in the result. 
Result so far: 4.0
The remainder is 626 after subtracting 3360 from 3986.
Grab the next digit (3) from the dividend, add it to 626, then carry on: 6263 / 840

Moving on to step 5:
840 can be fit into 6263 7 times, resulting in a remainder of 383.
Use 7 as the next digit of our solution. 
Result so far: 47.0
If we take 5880 away from 6263, we end up with 383.
Bring next digit (5) of the dividend behind the 383 and repeat the process: 3835 / 840

Moving on to step 6:
840 goes into 3835 4 times with a remainder of 475.
Use 4 as the next digit of our solution. 
Result so far: 474.0
The remainder is 475 after subtracting 3360 from 3835.
Include the next digit (7) from the dividend after 475, then repeat: 4757 / 840

Moving on to step 7:
If we divide 4757 by 840, we get 5 and a remainder of 557.
Write down 5 as next digit of the result. 
Result so far: 4745.0
Subtract 4200 from 4757 to get 557.
Since there are no more digits in the dividend, we add a zero to the remainder making it 5570, and continue the process.

Advancing to step 8:
The number 840 fits into 5570 6 times, leaving a remainder of 530.
Record the quotient 6 as the next digit in the result. 
Result so far: 4745.6
The remainder is 530 after subtracting 5040 from 5570.
Since there are no more digits in the dividend, we add a zero to the remainder making it 5300, and continue the process.

Moving on to step 9:
840 can be fit into 5300 6 times, resulting in a remainder of 260.
Use 6 as the next digit of our solution. 
Result so far: 4745.66
Subtract 5040 from 5300 to get 260.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2600, and continue the process.

Our division results in 4745.66 with a remaining 0.26.