4.NBT.B.4 Subtraction with regrouping. Always borrow before regrouping. When going across a zero, change it to a 9. When stopping at a zero, it becomes a 10.
4.NBT.B.4 Subtraction with regrouping. Always borrow before regrouping. When going across a zero, change it to a 9. When stopping at a zero, it becomes a 10.
