We're dividing 421423 by 78 
The aim is to understand the frequency of 78 in 421423.

On to step 1:
78 can be fit into 4 0 times, resulting in a remainder of 4.
Write down 0 as next digit of the result. 
Result so far: 0.0
Subtract 0 from 4 to get 4.
Append the next digit (2) from the dividend to 4 and continue with: 42 / 78

Advancing to step 2:
78 goes into 42 0 times with a remainder of 42.
Write down 0 as next digit of the result. 
Result so far: 0.0
If we take 0 away from 42, we end up with 42.
Grab the next digit (1) from the dividend, add it to 42, then carry on: 421 / 78

Going ahead to step 3:
78 goes into 421 5 times with a remainder of 31.
Use 5 as the next digit of our solution. 
Result so far: 5.0
Subtracting 390 from 421 leaves us with 31.
Fetch the next digit (4) from the dividend, attach it to 31 and continue: 314 / 78

Advancing to step 4:
78 can be fit into 314 4 times, resulting in a remainder of 2.
Put 4 as the next digit of the answer. 
Result so far: 54.0
The remainder is 2 after subtracting 312 from 314.
Grab the next digit (2) from the dividend, add it to 2, then carry on: 22 / 78

Moving on to step 5:
22 divided by 78 is 0 with a remainder of 22.
Record the quotient 0 as the next digit in the result. 
Result so far: 540.0
If we take 0 away from 22, we end up with 22.
Grab the next digit (3) from the dividend, add it to 22, then carry on: 223 / 78

Moving on to step 6:
The number 78 fits into 223 2 times, leaving a remainder of 67.
The number 2 becomes the next digit in our result. 
Result so far: 5402.0
The remainder is 67 after subtracting 156 from 223.
Since there are no more digits in the dividend, we add a zero to the remainder making it 670, and continue the process.

Going ahead to step 7:
The number 78 fits into 670 8 times, leaving a remainder of 46.
Put 8 as the next digit of the answer. 
Result so far: 5402.8
If we take 624 away from 670, we end up with 46.
Since there are no more digits in the dividend, we add a zero to the remainder making it 460, and continue the process.

Moving on to step 8:
The number 78 fits into 460 5 times, leaving a remainder of 70.
Write down 5 as next digit of the result. 
Result so far: 5402.85
If we take 390 away from 460, we end up with 70.
Since there are no more digits in the dividend, we add a zero to the remainder making it 700, and continue the process.

Going ahead to step 9:
The number 78 fits into 700 8 times, leaving a remainder of 76.
Record the quotient 8 as the next digit in the result. 
Result so far: 5402.858
If we subtract 624 from 700, we get 76.
Since there are no more digits in the dividend, we add a zero to the remainder making it 760, and continue the process.

Advancing to step 10:
The number 78 fits into 760 9 times, leaving a remainder of 58.
The number 9 becomes the next digit in our result. 
Result so far: 5402.8589
If we subtract 702 from 760, we get 58.
Since there are no more digits in the dividend, we add a zero to the remainder making it 580, and continue the process.

On to step 11:
If we divide 580 by 78, we get 7 and a remainder of 34.
Use 7 as the next digit of our solution. 
Result so far: 5402.85897
Subtract 546 from 580 to get 34.
Since there are no more digits in the dividend, we add a zero to the remainder making it 340, and continue the process.

On to step 12:
When dividing 340 by 78, we get 4 with a remainder of 28.
Record the quotient 4 as the next digit in the result. 
Result so far: 5402.858974
Deduct 312 from 340 and we're left with 28.
Since there are no more digits in the dividend, we add a zero to the remainder making it 280, and continue the process.

On to step 13:
78 can be fit into 280 3 times, resulting in a remainder of 46.
Use 3 as the next digit of our solution. 
Result so far: 5402.8589743
If we subtract 234 from 280, we get 46.
Since there are no more digits in the dividend, we add a zero to the remainder making it 460, and continue the process.

Let's proceed to step 14:
If we divide 460 by 78, we get 5 and a remainder of 70.
The number 5 becomes the next digit in our result. 
Result so far: 5402.85897435
Deduct 390 from 460 and we're left with 70.
Since there are no more digits in the dividend, we add a zero to the remainder making it 700, and continue the process.

In conclusion, the division gives 5402.85897435 with a balance of 7e-08.