Copy the visible number in a cell, not the actual number?

Copy the visible number in a cell, not the actual number?

Say in A1, B1, C1 I have this.....
20.777 | 30.88 | 40
And say I want them all to have 1 decimal place, so I click the "change
number of decimal places" button and get this.....
20.7 | 30.8 | 40.0
Now I want to display all three of those numbers in a single cell, in D1
The problem is i'm getting: "20.777 30.88 40"
Whereas I want to get: "20.7 30.8 40.0"
How do I copy over the visible number with 1 decimal place, rather than
the actual number? This is the formula Im using in D1: =A1&" "&B1&" "&C1