Skill: Subtract across zeros

When subtracting across zeros, regroup from a place to the left. A zero cannot give you any units, so keep moving left until you reach a nonzero digit.

Example:

$$500-276$$

Write the numbers by place value:

1. You cannot subtract $6$ ones from $0$ ones. Regroup $1$ hundred as $10$ tens:

$$5\text{ hundreds}=4\text{ hundreds }10\text{ tens}$$

2. You still cannot subtract $6$ ones from $0$ ones. Regroup $1$ ten as $10$ ones:

$$10\text{ tens}=9\text{ tens }10\text{ ones}$$

Now the top number is $4$ hundreds, $9$ tens, and $10$ ones.

3. Subtract each place:

   • Ones: $10-6=4$
   • Tens: $9-7=2$
   • Hundreds: $4-2=2$

Therefore,

$$500-276=224$$

The value of $500$ did not change; it was simply renamed as $4$ hundreds, $9$ tens, and $10$ ones.