661388 divided by 78 
The aim is to understand the frequency of 78 in 661388.

Going ahead to step 1:
When dividing 6 by 78, we get 0 with a remainder of 6.
Write down 0 as next digit of the result. 
Result so far: 0.0
The remainder is 6 after subtracting 0 from 6.
Fetch the next digit (6) from the dividend, attach it to 6 and continue: 66 / 78

Moving on to step 2:
When dividing 66 by 78, we get 0 with a remainder of 66.
Write down 0 as next digit of the result. 
Result so far: 0.0
The remainder is 66 after subtracting 0 from 66.
Take the next digit (1) from the dividend and append it to 66, then repeat: 661 / 78

Let's proceed to step 3:
78 goes into 661 8 times with a remainder of 37.
Write down 8 as next digit of the result. 
Result so far: 8.0
If we subtract 624 from 661, we get 37.
Fetch the next digit (3) from the dividend, attach it to 37 and continue: 373 / 78

Moving on to step 4:
When dividing 373 by 78, we get 4 with a remainder of 61.
Write down 4 as next digit of the result. 
Result so far: 84.0
Subtract 312 from 373 to get 61.
Grab the next digit (8) from the dividend, add it to 61, then carry on: 618 / 78

Moving on to step 5:
618 divided by 78 is 7 with a remainder of 72.
Record the quotient 7 as the next digit in the result. 
Result so far: 847.0
Deduct 546 from 618 and we're left with 72.
Grab the next digit (8) from the dividend, add it to 72, then carry on: 728 / 78

On to step 6:
78 goes into 728 9 times with a remainder of 26.
Put 9 as the next digit of the answer. 
Result so far: 8479.0
Deduct 702 from 728 and we're left with 26.
Since there are no more digits in the dividend, we add a zero to the remainder making it 260, and continue the process.

Step 7:
When dividing 260 by 78, we get 3 with a remainder of 26.
The next digit of our result is 3. 
Result so far: 8479.3
Deduct 234 from 260 and we're left with 26.
Since there are no more digits in the dividend, we add a zero to the remainder making it 260, and continue the process.

Going ahead to step 8:
When dividing 260 by 78, we get 3 with a remainder of 26.
Record the quotient 3 as the next digit in the result. 
Result so far: 8479.33
Subtracting 234 from 260 leaves us with 26.
Since there are no more digits in the dividend, we add a zero to the remainder making it 260, and continue the process.

In conclusion, the division gives 8479.33 with a balance of 0.026.