Update several fields within certain rows

[h12]

Hi all

I have the following data set (Note, the original data set has over 1mil rows)

A	B	C	D	E	F	G
[Null]	1	[Null]	[Null]	[Null]	4	65
[Null]	2	[Null]	[Null]	[Null]	7	87
[Null]	3	[Null]	[Null]	[Null]	8	9

I essentially want to update the [NULL] fields to 'N/A' in one go. I can update it using a formula tool but that takes some time as the main data set has 10+ columns which contain [NULLS] which I need to update.

Final output to look like

A	B	C	D	E	F	G
N/A	1	N/A	N/A]	N/A	4	65
N/A	2	N/A	N/A	N/A	7	87
N/A	3	N/A	N/A	N/A	8	9

Many thanks

[h12]

Thank you @Jean-Balteryx  @atcodedog05 ! Not sure how I missed that top bit!