54342603 divided by 390 
The aim is to understand the frequency of 390 in 54342603.

Advancing to step 1:
The number 390 fits into 5 0 times, leaving a remainder of 5.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
Deduct 0 from 5 and we're left with 5.
Bring next digit (4) of the dividend behind the 5 and repeat the process: 54 / 390

Advancing to step 2:
If we divide 54 by 390, we get 0 and a remainder of 54.
Put 0 as the next digit of the answer. 
Result so far: 0.0
Subtracting 0 from 54 leaves us with 54.
Take the next digit (3) from the dividend and append it to 54, then repeat: 543 / 390

Step 3:
When dividing 543 by 390, we get 1 with a remainder of 153.
Write down 1 as next digit of the result. 
Result so far: 1.0
Subtract 390 from 543 to get 153.
Include the next digit (4) from the dividend after 153, then repeat: 1534 / 390

Going ahead to step 4:
If we divide 1534 by 390, we get 3 and a remainder of 364.
Put 3 as the next digit of the answer. 
Result so far: 13.0
If we take 1170 away from 1534, we end up with 364.
Append the next digit (2) from the dividend to 364 and continue with: 3642 / 390

Moving on to step 5:
When dividing 3642 by 390, we get 9 with a remainder of 132.
Record the quotient 9 as the next digit in the result. 
Result so far: 139.0
If we take 3510 away from 3642, we end up with 132.
Bring next digit (6) of the dividend behind the 132 and repeat the process: 1326 / 390

Going ahead to step 6:
1326 divided by 390 is 3 with a remainder of 156.
Use 3 as the next digit of our solution. 
Result so far: 1393.0
If we subtract 1170 from 1326, we get 156.
Include the next digit (0) from the dividend after 156, then repeat: 1560 / 390

Going ahead to step 7:
The number 390 fits into 1560 4 times, leaving a remainder of 0.
The next digit of our result is 4. 
Result so far: 13934.0
If we take 1560 away from 1560, we end up with 0.
Take the next digit (3) from the dividend and append it to 0, then repeat: 3 / 390

Moving on to step 8:
The number 390 fits into 3 0 times, leaving a remainder of 3.
Record the quotient 0 as the next digit in the result. 
Result so far: 139340.0
If we subtract 0 from 3, we get 3.
Since there are no more digits in the dividend, we add a zero to the remainder making it 30, and continue the process.

Advancing to step 9:
390 goes into 30 0 times with a remainder of 30.
Use 0 as the next digit of our solution. 
Result so far: 139340.0
Deduct 0 from 30 and we're left with 30.
Since there are no more digits in the dividend, we add a zero to the remainder making it 300, and continue the process.

Advancing to step 10:
390 goes into 300 0 times with a remainder of 300.
Use 0 as the next digit of our solution. 
Result so far: 139340.0
If we take 0 away from 300, we end up with 300.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3000, and continue the process.

The final outcome is 139340.0, with a leftover of 0.3.