We divide 702506 by 21
The aim is to understand the frequency of 21 in 702506.

Step 1:
When dividing 7 by 21, we get 0 with a remainder of 7.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
If we take 0 away from 7, we end up with 7.
Bring next digit (0) of the dividend behind the 7 and repeat the process: 70 / 21

Advancing to step 2:
70 divided by 21 is 3 with a remainder of 7.
The next digit of our result is 3. 
Result so far: 3.0
Subtract 63 from 70 to get 7.
Bring next digit (2) of the dividend behind the 7 and repeat the process: 72 / 21

On to step 3:
When dividing 72 by 21, we get 3 with a remainder of 9.
The next digit of our result is 3. 
Result so far: 33.0
Deduct 63 from 72 and we're left with 9.
Fetch the next digit (5) from the dividend, attach it to 9 and continue: 95 / 21

Advancing to step 4:
21 can be fit into 95 4 times, resulting in a remainder of 11.
Record the quotient 4 as the next digit in the result. 
Result so far: 334.0
Subtracting 84 from 95 leaves us with 11.
Grab the next digit (0) from the dividend, add it to 11, then carry on: 110 / 21

Let's proceed to step 5:
21 goes into 110 5 times with a remainder of 5.
Use 5 as the next digit of our solution. 
Result so far: 3345.0
Subtract 105 from 110 to get 5.
Append the next digit (6) from the dividend to 5 and continue with: 56 / 21

Step 6:
56 divided by 21 is 2 with a remainder of 14.
Use 2 as the next digit of our solution. 
Result so far: 33452.0
The remainder is 14 after subtracting 42 from 56.
Since there are no more digits in the dividend, we add a zero to the remainder making it 140, and continue the process.

On to step 7:
21 can be fit into 140 6 times, resulting in a remainder of 14.
Record the quotient 6 as the next digit in the result. 
Result so far: 33452.6
Deduct 126 from 140 and we're left with 14.
Since there are no more digits in the dividend, we add a zero to the remainder making it 140, and continue the process.

Step 8:
If we divide 140 by 21, we get 6 and a remainder of 14.
The number 6 becomes the next digit in our result. 
Result so far: 33452.66
Deduct 126 from 140 and we're left with 14.
Since there are no more digits in the dividend, we add a zero to the remainder making it 140, and continue the process.

After the division, we end up with 33452.66 and a remainder of 0.014.