We look at the division of 21220899 by 225 
The aim is to understand the frequency of 225 in 21220899.

Going ahead to step 1:
The number 225 fits into 2 0 times, leaving a remainder of 2.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
Subtract 0 from 2 to get 2.
Append the next digit (1) from the dividend to 2 and continue with: 21 / 225

Step 2:
225 goes into 21 0 times with a remainder of 21.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
The remainder is 21 after subtracting 0 from 21.
Append the next digit (2) from the dividend to 21 and continue with: 212 / 225

Advancing to step 3:
If we divide 212 by 225, we get 0 and a remainder of 212.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
The remainder is 212 after subtracting 0 from 212.
Grab the next digit (2) from the dividend, add it to 212, then carry on: 2122 / 225

Advancing to step 4:
225 can be fit into 2122 9 times, resulting in a remainder of 97.
Record the quotient 9 as the next digit in the result. 
Result so far: 9.0
If we take 2025 away from 2122, we end up with 97.
Include the next digit (0) from the dividend after 97, then repeat: 970 / 225

Advancing to step 5:
If we divide 970 by 225, we get 4 and a remainder of 70.
Write down 4 as next digit of the result. 
Result so far: 94.0
Subtracting 900 from 970 leaves us with 70.
Append the next digit (8) from the dividend to 70 and continue with: 708 / 225

Step 6:
The number 225 fits into 708 3 times, leaving a remainder of 33.
Write down 3 as next digit of the result. 
Result so far: 943.0
Subtract 675 from 708 to get 33.
Grab the next digit (9) from the dividend, add it to 33, then carry on: 339 / 225

Going ahead to step 7:
225 can be fit into 339 1 times, resulting in a remainder of 114.
Record the quotient 1 as the next digit in the result. 
Result so far: 9431.0
If we subtract 225 from 339, we get 114.
Append the next digit (9) from the dividend to 114 and continue with: 1149 / 225

Going ahead to step 8:
225 can be fit into 1149 5 times, resulting in a remainder of 24.
The next digit of our result is 5. 
Result so far: 94315.0
If we subtract 1125 from 1149, we get 24.
Since there are no more digits in the dividend, we add a zero to the remainder making it 240, and continue the process.

Moving on to step 9:
If we divide 240 by 225, we get 1 and a remainder of 15.
The next digit of our result is 1. 
Result so far: 94315.1
If we subtract 225 from 240, we get 15.
Since there are no more digits in the dividend, we add a zero to the remainder making it 150, and continue the process.

Moving on to step 10:
When dividing 150 by 225, we get 0 with a remainder of 150.
Write down 0 as next digit of the result. 
Result so far: 94315.1
If we subtract 0 from 150, we get 150.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1500, and continue the process.

Going ahead to step 11:
If we divide 1500 by 225, we get 6 and a remainder of 150.
Use 6 as the next digit of our solution. 
Result so far: 94315.106
If we subtract 1350 from 1500, we get 150.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1500, and continue the process.

On to step 12:
225 goes into 1500 6 times with a remainder of 150.
Write down 6 as next digit of the result. 
Result so far: 94315.1066
Subtracting 1350 from 1500 leaves us with 150.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1500, and continue the process.

The final outcome is 94315.1066, with a leftover of 0.0015.