Bulk IP address and Subnet mask to CIDR conversion

I have a task to convert a whole heap of IP address to their CIDR notation and would like to do this in Excel

I have
Column A = IP Address
Column B = Subnet Mask
ie
10.227.68.2 255.255.255.0
10.227.69.2 255.255.254.0
10.227.80.192 255.255.255.128


On another worksheet i have a table with the subnet and CIDR so i can do a VLOOKUP
ie
....
255.255.252.0 /22
255.255.254.0 /23
255.255.255.0 /24
255.255.255.128 /25
255.255.255.192 /26
....

Would like a formula that can then take that information and create the full CIDR notation in column C
Network ID/CIDR

From the above example the output should be:
10.227.68.2 255.255.255.0 10.227.68.0/24
10.227.71.2 255.255.254.0 10.227.70.0/23
10.227.80.192 255.255.255.128 10.227.80.128/25

I have failed multiple times in creating this and there is a lot of forums asking for the opposite CIDR to subnet mask

Welcome to the forum.

Will you please attach a small sample Excel workbook? We are not able to work with or manipulate a picture of one and nobody wants to have to recreate your data from scratch.

1. Make sure that your sample data are REPRESENTATIVE of your real data. The use of unrepresentative data is very frustrating and can lead to long delays in reaching a solution.

2. Make sure that your desired results are also shown (mock up the results manually).

3. Make sure that all confidential data is removed or replaced with dummy data first (e.g. names, addresses, E-mails, etc.).

4. Try to avoid using merged cells as they cause lots of problems.

Unfortunately the attachment icon doesn't work at the moment, so to attach an Excel file you have to do the following: just before posting, scroll down to Go Advanced and then scroll down to Manage Attachments. Now follow the instructions at the top of that screen.

Please pay particular attention to point 2 (above): without an idea of your intended outcomes, it is often very difficult to offer appropriate advice.