Adding and Subtracting Decimals Games and Activities

How Can I Help My Child Add and Subtract Decimals?

Remind your child to make sure that the decimal place in the sum remains the same when adding and subtracting decimals. For instance, consider the following problem: 5.31 - 2.45. Both integers have decimals in the hundredth place, so the answer (2.86) also has decimals in the hundredth place. You can help by providing your child with graph paper, which may help him or her keep the decimal place lined up. You could also look over your child's homework before he or she turns it in.

Subtracting decimals can be confusing to some students when it involves borrowing numbers; however, your child will follow the same process as normal. For instance, when subtracting 1.20 - 1.05, your child must first borrow a one from the tenths column and then subtract as usual. The answer is 0.15.

Games and Activities

Money

Thinking about decimals in terms of money may help your child understand the concept. It also provides a tangible way for your child to manipulate a problem. For a problem like 3.50 + 1.25 = 4.75, give your child four dollar bills and three quarters.

Similarly, use money to work with subtraction. If your child has $5 and buys something worth $1.15, he or she can use subtraction to find out how much money would be left after the purchase (5.00 - 1.15 = 3.85). Once your child has gotten a firm foundation in adding and subtracting money, you can give him or her a few problems that only involve decimals (without the context of money) and explain the similarities.

Decimal Match-Up

Write a variety of decimals on note cards and shuffle them on the table. Include decimals like 0.20, 0.80, 0.25 and 0.75. Encourage your child to find decimal combinations that add up to 1.00. This game requires children to practice addition. For example, 0.20 + 0.80 = 1.00. Take turns with your child and whoever finds the most combinations wins.

Find the Number

Ask your child to become a detective and find the missing number in the following equation: 3.40 + x = 5.00. Use subtraction to solve: 5.00 - 3.40 = 1.60. Encourage your child to check his or her answer by inserting the number back into the original equation (3.40 + 1.60 = 5.00).

This game requires higher order thinking skills and will likely be a challenge for your child. However, it can also be a lot of fun. Make sure you're available to help your child.