# Surf for More Math

## Lesson 5 **- Adding and Subtracting Decimal Numbers**

To encourage your child to have fun on the Web
while learning about Adding and Subtracting Decimal Numbers, here are
some games and interactive activities they can do on their own or in
pairs.

**Goal**

Use mental math strategies to calculate sums and differences.

**Builds Upon**

Student Book page 120

### Instructions for Use

** **

Adding
Money** **prompts your child to add sums of money.

To use Adding Money, click
the 'Start Addition' button. Using paper and a pencil, place the number
to be added below the first number so that the thousands, hundreds,
tens and ones places are aligned. Draw a line under the bottom number.
Add the bottom place digits to the top ones and regroup where necessary.
When your child has finished adding the numbers, input the answer in
the text field and click 'Check'.

** **

** **

Change
Maker provides your child with practice counting money and estimating
differences.

To use Change Maker, choose a currency by clicking on the flag of a
country, and a difficulty level. Mentally subtract how much money you
expect to get back when you pay for an item. If the answer is correct,
the amount of change is added to the piggy bank. If the answer is wrong,
the correct amount of change is subtracted from the piggy bank. The
more money in your piggy bank, the harder the questions will get.