In this activity, we will be looking at how to round numbers to the **nearest 100 **in order to estimate the answer to a multiplication.

**Rules for rounding to the nearest 100**

If the tens digit is** less than 50**, the number is **rounded down.**

If the tens digit is **50 or more, **the number is **rounded up.**

Estimate the answer by rounding the numbers to the nearest 100 before adding.

We can ignore the 'ones' digit when rounding a 3 digit number to the nearest 100.

744 would be rounded **down **to 700.

751 would be rounded** up **to 800.

8,264 would be rounded** up **to 8,300

**Example**

**242 x 164 = ?**

Round each number first

242 200

164 200

Now calculate: **200 x 200 = ?**

2 x 2 x 100 x 100 = 4 x 10,000 = **40,000**

**Top tip!**

When multiplying large numbers with zeros, remove the zeros first, multiply the remaining digits and then add the zeros back!

200 x 200 Remove the four zeros: 2 x 2 = 4

Add the four zeros back on: 40,000

Easy, isn't it?!

Let's get started then!