In this activity, we will **add **or **subtract 100, 10 or 1** to or from a number.

When we add or subtract **100**, it is the **hundreds **digit that we change.

When we add or subtract **10**, it is the **tens **digit that we change.

When we add or subtract **1**, it is the **ones **digit that we change.

Remember that *other *digits may have to change too.

**Example 1**

What number is **100** **less **than **750**?

**Answer**

**Reduce 7 hundred** by 1 hundred to get **6 hundred**...

750 becomes **650**

**Example 2**

What number is **10 more** than **539**?

**Answer**

**Increase** **3 tens** by 1 ten to get **4 tens**...

539 becomes** 549**

**Example 3**

What number is **1 less** than **539**?

**Answer**

**Reduce** **9 ones** by 1 one to get** 8 ones**...

539 becomes** 538**

**Example 4**

What number is **10 less** than **405**?

__Answer__

Here we have to be careful, because we can't reduce the tens digit by 1.

So include the hundreds digit.

Think of it as **reducing ****40 tens** by 1 ten to get** 39 tens**.

405 becomes **395**

That was a hard one to finish with, so make sure you've understood it before attempting the questions.