How to calculate swiss IBAN account number manually?

The swiss iban format are of 21 digits consisting of 4 parts.
1. Country code: CH - 2 characters
2. Control Digit (XX) 2 digits
3. Bank Clearing number (BC nummer) 5 digits
4. Account Number (12 digits)
It is not necessary that, the iban may contain only numbers, but can also have alpha-numeric characters. As you notice from the above parameters, we have all necessary data for iban but 'Control digit' is missing. For that see the procedure below.
Goal: To calculate control digit of IBAN from account number, and bc number. You can find the BC number of the swiss bank, here. Banks are grouped according to city/town name in switzerland.
For example, your account number is A-10.2450.26.01 and your account is with
CREDIT SUISSE (5) (Main Branch)
Bahnhofstrasse 53
Postfach 4879
Zürich
CH-8021
BC number : 554
Step 1:
First, padd your account number in 12 digit format, by padding zeros in the front. Strip off all the hyphens, dots and commas. Just make it plain.
Account number: 0A1024502601
Step 2:
Pad the BC number of the bank by zeros in front, if it is less than 5 digits.
BC number: 00554
Step 3:
Concatenate (Join) )your BC number and account number. This becomes
005540A1024502601 (17)
Step 4:
Again join the step 3 value to: 'CH00'
005540A1024502601CH00
Step 5:
In this step, you must convert the whole result from step 4 into numbers, according the table given below, by eliminating alphabet characters.

A	10	N	23
B	11	O	24
C	12	P	25
D	13	Q	26
E	14	R	27
F	15	S	28
G	16	T	29
H	17	U	30
I	18	V	31
J	19	W	32
K	20	X	33
L	21	Y	34
M	22	Z	35

005540A1024502601CH00 becomes 005540101024502601121700
Step 6:
Now, you have to perform a modulo 97 operation on the result derived from step 5 and find that result
00554010102450260121700 mod 97
The result = 20
Step 7:
In this step, we will catch hold of control digits, because once we get control digits, then the data required for iban number is complete.
Subtract 20 from 98:
98 - 20 = 78
This is our controol digit.
Now, fill in the IBAN slots with our data.
Country Code: CH (2)
Control Digit: 78 (2)
BC Number : 00554 (5)
Account number: 0A1024502601 (12)
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CH72005540A1024502601 (21) which is your IBAN number

CH78 0055 40A1 0245 0260 1

(An IBAN is always grouped in 4s separated by blans, when quoted in paper format).