sum difference between 2 months for various meter readings

[Deanius]

Hi

I want to know if there is a way of showing the difference between two numbers between one month and the next for multiple serial numbers

below shows one serial number with a running total for the device monthly. There would be other serial numbers in the mix also. I need too know the difference between each month per device.

the differnence between Nov/16 and Dec/16 total count is 6896 so i'd need 6896 to be in the Nov/16 row for the serial number A5C2121008007

Hope this makes sense. Thanks in advance.

Dean

Serial Number	Total Count	Mono Count	Colour Count	Scans	Date
'A5C2121008007	141422	72214	69208	10440	01/11/2016
'A5C2121008007	148318	75996	72322	10969	01/12/2016
'A5C2121008007	157247	80815	76432	11793	01/01/2017
'A5C2121008007	164505	84302	80203	12459	01/02/2017
'A5C2121008007	171779	87893	83886	13145	01/03/2017
'A5C2121008007	179529	91605	87924	13792	01/04/2017
'A5C2121008007	188118	96094	92024	14546	01/05/2017
'A5C2121008007	197671	100801	96870	15562	01/06/2017
'A5C2121008007	206846	105177	101669	16522	01/07/2017
'A5C2121008007	215118	109483	105635	17129	01/08/2017
'A5C2121008007	223532	113748	109784	17676	01/09/2017
'A5C2121008007	231728	117677	114051	18366	01/10/2017
'A5C2121008007	240447	121865	118582	19180	01/11/2017
'A5C2121008007	245792	124579	121213	19661	01/12/2017
'A5C2121008007	255086	129047	126039	20247	01/01/2018
'A5C2121008007	263910	133841	130069	20851	01/02/2018
'A5C2121008007	271674	137464	134210	21581	01/03/2018

<colgroup><col style="mso-width-source:userset;mso-width-alt:3516;width:78pt" width="104"> <col style="mso-width-source:userset;mso-width-alt:2991;width:67pt" width="89"> <col style="mso-width-source:userset;mso-width-alt:3193;width:71pt" width="95"> <col style="mso-width-source:userset;mso-width-alt:3314;width:74pt" width="98"> <col style="width:50pt" width="67"> <col style="mso-width-source:userset;mso-width-alt:3072;width:68pt" width="91"> </colgroup><tbody>
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[offthelip]

something like this should do ti. I have assume the last row is 200

=INDEX(B2:B$200,MATCH(A2,A3:A$200,0))-B2