In this worksheet, you will be asked to round decimal numbers to the nearest whole number and then estimate the answer to an addition.

**Recap of rounding:**

**What is 35 rounded to the nearest 10?**

If the 'one' of the number is less than 5, the number needs to be rounded down.

If the 'one' of the number is 5 or above, the number needs to be rounded up.

So 35 would be rounded up to **40****.**

**What is 834 rounded to the nearest 100?**

834 would be rounded down to **800 **because the tens digit is less than 50 so the number is rounded down.

**What is 3.9 rounded to the nearest whole number?**

Answer: **4**

Look at the number after the decimal point, 9. Because it's more than 5, you round the 3 to the left of it, up to 4.

**What is 8.42 rounded to one decimal place?**

Answer: **8.4**

Look at the second digit after the decimal point, 2. Because it is less than 5, you leave the 4 to the left of it the same.

**Example:**

Estimate the answer to the addition by first rounding the decimal number.

**10 + 1.42 =** **10 + 1.4 = 11.4**