21640814 ÷ 406 
The aim is to understand the frequency of 406 in 21640814.

On to step 1:
When dividing 2 by 406, we get 0 with a remainder of 2.
Put 0 as the next digit of the answer. 
Result so far: 0.0
If we take 0 away from 2, we end up with 2.
Take the next digit (1) from the dividend and append it to 2, then repeat: 21 / 406

Let's proceed to step 2:
21 divided by 406 is 0 with a remainder of 21.
The next digit of our result is 0. 
Result so far: 0.0
Subtracting 0 from 21 leaves us with 21.
Append the next digit (6) from the dividend to 21 and continue with: 216 / 406

On to step 3:
If we divide 216 by 406, we get 0 and a remainder of 216.
The next digit of our result is 0. 
Result so far: 0.0
Subtract 0 from 216 to get 216.
Include the next digit (4) from the dividend after 216, then repeat: 2164 / 406

Let's proceed to step 4:
If we divide 2164 by 406, we get 5 and a remainder of 134.
The next digit of our result is 5. 
Result so far: 5.0
The remainder is 134 after subtracting 2030 from 2164.
Grab the next digit (0) from the dividend, add it to 134, then carry on: 1340 / 406

Let's proceed to step 5:
If we divide 1340 by 406, we get 3 and a remainder of 122.
The number 3 becomes the next digit in our result. 
Result so far: 53.0
Subtract 1218 from 1340 to get 122.
Include the next digit (8) from the dividend after 122, then repeat: 1228 / 406

Advancing to step 6:
When dividing 1228 by 406, we get 3 with a remainder of 10.
Record the quotient 3 as the next digit in the result. 
Result so far: 533.0
Deduct 1218 from 1228 and we're left with 10.
Bring next digit (1) of the dividend behind the 10 and repeat the process: 101 / 406

On to step 7:
406 can be fit into 101 0 times, resulting in a remainder of 101.
Put 0 as the next digit of the answer. 
Result so far: 5330.0
If we take 0 away from 101, we end up with 101.
Include the next digit (4) from the dividend after 101, then repeat: 1014 / 406

Moving on to step 8:
406 can be fit into 1014 2 times, resulting in a remainder of 202.
The next digit of our result is 2. 
Result so far: 53302.0
If we subtract 812 from 1014, we get 202.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2020, and continue the process.

On to step 9:
2020 divided by 406 is 4 with a remainder of 396.
Write down 4 as next digit of the result. 
Result so far: 53302.4
Subtract 1624 from 2020 to get 396.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3960, and continue the process.

Moving on to step 10:
3960 divided by 406 is 9 with a remainder of 306.
The next digit of our result is 9. 
Result so far: 53302.49
Deduct 3654 from 3960 and we're left with 306.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3060, and continue the process.

Moving on to step 11:
If we divide 3060 by 406, we get 7 and a remainder of 218.
Record the quotient 7 as the next digit in the result. 
Result so far: 53302.497
If we subtract 2842 from 3060, we get 218.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2180, and continue the process.

Moving on to step 12:
2180 divided by 406 is 5 with a remainder of 150.
The number 5 becomes the next digit in our result. 
Result so far: 53302.4975
The remainder is 150 after subtracting 2030 from 2180.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1500, and continue the process.

Moving on to step 13:
406 goes into 1500 3 times with a remainder of 282.
Use 3 as the next digit of our solution. 
Result so far: 53302.49753
If we subtract 1218 from 1500, we get 282.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2820, and continue the process.

On to step 14:
When dividing 2820 by 406, we get 6 with a remainder of 384.
Write down 6 as next digit of the result. 
Result so far: 53302.497536
If we take 2436 away from 2820, we end up with 384.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3840, and continue the process.

Advancing to step 15:
The number 406 fits into 3840 9 times, leaving a remainder of 186.
Write down 9 as next digit of the result. 
Result so far: 53302.4975369
Subtract 3654 from 3840 to get 186.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1860, and continue the process.

Advancing to step 16:
If we divide 1860 by 406, we get 4 and a remainder of 236.
The next digit of our result is 4. 
Result so far: 53302.49753694
Deduct 1624 from 1860 and we're left with 236.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2360, and continue the process.

The quotient of the division is 53302.49753694, and the remainder is 2.36e-07.