How to add this type of data

or, you can use custom formats to do it, to "show" the cells with the " m" on, but in fact they're just numbers with no " m"

If you select the cells with the numbers in, and do Format.. Cells.. Custom and then type the following into the Type box:
0" m";0" m";0" m";
then you can just enter a number into the box ie 2 and it will be displayed as 2 m
you can then sum the numbers automatically.

how the line above works:
the bit before the 1st ; is the format applied to positive numbers
the bit before the 2nd ; is for negative numbers
the bit before the 3rd is for zero values
and the end is for text values.

more info in the Excel help - look for "create a custom number format"

If you use it a lot, keep some cells formatted with it, and use the Format Painter (brush button) to apply it.
If you get the data in from somewhere else, and it already has the " m" attached, you can always do a Find/Replace for the " m" to convert them back to numbers, then apply the format as above.  

oh, when I said "you can sum the numbers automatically", I meant "you can sum the numbers normally"...

Copy the cells,

Go to a fresh row, click in a single cell

Edit/Paste special celik the transpose box.

The values should now be in a row, you can delete the original cell/rows is required.

M

Dear Mr. Byundt,

I tried the way you told me but it doesn't work, it gives #NAME? error. Let me explain my question again. Kindly what should be the easiest way to add these numbers below.

15 m
12 m
23 m
43 m

Regards
Jamil Ahmed

Jamil Ahmed,
I assumed from your initial question that the cells contained a text string like "15 m". If so, the formula suggested will definitely add it--with the result being 93. In this case, the following formula should return TRUE:
=ISTEXT(A1)      Formula assumes that one of the cells being added is cell A1

If the cells contain a pure number, only formatted to show the m, then the formula will still add those four numbers and get the correct answer 93 m  (assuming the same formatting). In this situation, the following formula should return FALSE:
=ISTEXT(A1)

One way I can get a #NAME? error is if I spell the name of the function incorrectly--such as if I were using a French version of Excel. In that case, the formula should be:
=SOMME(GAUCHE(A1:A4;NBCAR(A1:A4)-2)*1)
Note the use of semicolon instead of comma, and SOMME, GAUCHE and NBCAR instead of SUM, LEFT and LEN.

The other way I can get a #NAME? error is if the worksheet uses R1C1 addressing for cells. This is changed back to A1 style addressing using the Tools...Options...General menu item by unchecking the "R1C1 Reference Style" checkbox.

If neither of these possibilities applies to your situation, then the next step would be to look at your workbook. The best way to do this is to post a link to it. I'll do that for you if you don't have a way of doing it yourself. My e-mail address is in my EE user profile--just double-click on my name at the top of this Comment.
Brad