Column addition with the carried digits written where they actually go.
First number · Second number
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Regrouping shown the way it is written on paper — crossed out, with the new number above.
When the neighbour is a zero it has nothing to lend, so you keep going left. The hardest one in the unit.
Line up the points, fill the gaps with zeros, then add like normal.
The same lining-up rule, plus borrowing across the decimal point.