Tax question

In the instructions for form 1040, there is an “Itemized Deductions Worksheet—Line 29” which has

line10: Divide line 9 by 1.5
line11: Subtract line 10 from line 9

According to the above, if line9 = x, then line10 = x/1.5 and line11 = x - x/1.5 = x/3
So, why didn’t they just say

line11: Divide line 9 by 3

Am I missing something?

FYI: line10 is not used in the remainder of the worksheet, only line11 is, so I don’t see the rationale for calculating it.

The search for a method to the IRS’s madness is often unfulfilling. My WAG is that some other worksheet or schedule refers to line 10.

Good point. However, even if that were the case, since line10=line9/1.5 and line11=line9/3, couldn’t they simply have “line11=line9/3” in there, and then, in the other worksheet say something like “Take line11 from Itemized Deductions Worksheet and multiply it by 2”