multiply each digit by its place number

[kcmuppet]

Hi,

I've a bunch 12 digit numbers (precededed by a letter) for which I need to multiply each by its place value, and then add them together then apply some more maths to the result to produce a check digiit.

e.g. for X792515389001, I need to multiply the 7 by 2, add it to 9x3, 2x4 etc.

Is there a quicker way to do the multiplying than =sum(mid(A1,2,1)*2,mid(A1,3,1)*3,... etc?

Thanks

 

[Eric W]

Maybe:

=SUM(MID(A1,{2,3,4,5,6,7,8,9,10,11,12,13},1)*{2,3,4,5,6,7,8,9,10,11,12,13})

 

[kcmuppet]

Thanks Eric!

 

[Eric W]

You're welcome!

 

[Tetra201]

Not as elegant, but works (to be entered using Ctrl+Shift+Enter):

=SUM(--RIGHT(QUOTIENT(--MID(A1,2,12),10^(ROW(A1:A12)-1))&"")*(14-ROW(A1:A12)))

 

[Rick Rothstein]

Also not as elegant...

=SUMPRODUCT(MID(A1,ROW(2:13),1)*ROW(2:13))