Subtraction Across Zeros

Dear children,

How many ways can we do subtraction across zeros? Let’s find out! 🙂

Image result for subtraction across zeros trick
How cool is this? 🙂
Usual subtraction algorithm and box method
Box Method (from 1:53 onwards)
Convert to subtraction without regrouping (from 3:52), Box method (from 5:24 onwards)