Displaying Lakhs and Crores in Google Sheets

This works in Google Sheets for sure. Should work in Excel too.

With the appropriate cells selected, navigate to:

Google Sheets : Format -> Number -> More Formats -> Custom Number Format
Excel : Format -> Cells -> Custom -> [Custom text box]

Enter one of the following and Apply:

A] For Lakhs and Crores with the Rupee symbol and decimals

[$₹][>9999999]##\,##\,##\,##0.00;[$₹][>99999]##\,##\,##0.00;[$₹]##,##0.00

B] For Lakhs and Crores with the Rupee symbol and without decimals

[$₹][>9999999]##\,##\,##\,##0;[$₹][>99999]##\,##\,##0;[$₹]##,##0

C] For Lakhs and Crores without the Rupee symbol and with decimals

[>9999999]##\,##\,##\,##0.00;[>99999]##\,##\,##0.00;##,##0.00

D] For Lakhs and Crores without both the Rupee symbol and decimals

[>9999999]##\,##\,##\,##0;[>99999]##\,##\,##0;##,##0

Edit: I've tested these on both Google Sheets and Excel. Negative numbers work as well.

Indian currency format displays numbers like below

1 - One Rupee
10 - Ten Rupee
100 - One Hundred Rupee
1,000 - One Thousand Rupee
10,000 - Ten Thousand Rupee
1,00,000 - One Lac Rupee
10,00,000 - Ten Lac Rupee
1,00,00,000 - One Crore Rupee

So below formats seems to be correct.

To show positive and negative INR/Rs. up to Lakh

[>99999][$₹]##\,##\,##0.00;[<-99999][$₹]##\,##\,##0.00;[$₹]##\,##0.00

To add support for positive lakhs and crores

[>9999999][$₹]##\,##\,##\,##0.00;[>99999][$₹]##\,##\,##0.00;[$₹]##,##0.00

Add support for negative lakhs and crores

[<-9999999][$₹]##\,##\,##\,##0.00;[<-99999][$₹]##\,##\,##0.00;[$₹]##,##0.00

For Microsoft excel, add the above format at Format -> Cells -> Custom -> [Custom text box] Below screenshot demonstrates above custom format in use:

Reference: https://www.raghunayak.com/2020/07/how-to-show-inrrs-in-lakh-crore-format.html