# Package 1-5: Closest to 100

In this activity your child will play a game and use a variety of ways to record their scores.

Week 2 - Package 5 - Year 5 & 6 Mathematics - Closest to 100

# Things you need

Ideal Back up

Playing cards from Ace to 9 (where Ace = 1)

UNO Cards

4 sets of homemade cards with numbers 1-9

# Why is this activity important?

Games provide a rich context for developing mathematical reasoning. They also provide a motivating context to practise using a range of appropriate strategies when solving addition and subtraction problems. It is important to build students’ understandings of numbers to 100. Working in a group provides opportunities for students to talk about their strategies and give valid reasons for supporting one possible solution over another.

Before you start

• Setting up the activity with ample space to place cards in front of players

• Students are able to use a range of strategies to add and subtract up to 100

# What your child needs to know and do

Watch the video Closest to 100.

# What to do next

• Players shuffle the cards and put them in a central pile. One person takes 6 cards and places them face up for everyone to see.

• The goal is to use addition and subtraction to get as close to a total of 100 as possible.

• Each card can only be used once. It can be used to form a 1- or 2-digit number.

• Players score 0 points if they are able to reach exactly 100. Otherwise, they work out their points based on the difference between their total and 100. For example, if a team created a total of 98, they would score 2 points.

• Keep a cumulative total of their difference to 100. The winner is the team to have the lowest points score at the end.

Activity too hard? Activity too easy?

Change the target number to a smaller number (for example, 30)

Use more cards to find a solution

Use a number chart to 100 to assist with counting

Allow students to use a calculator to help them check their thinking.

Include multiplication and division in the challenge

Change the target number to a bigger number than 100 (for example, try 137 or 956)

Change the target number to a smaller number, for example, 35-hundredths (0.35). In this case, the numerals can be worth tenths or hundredths.

Use fewer cards to find a solution, or, change the rules so you use all the cards.

Do your solutions need to be under 100?

(Yes, as your solution may be 105 and therefore your score is 5. The other team may have a score of 90 and their score will be 10. The smallest difference wins.)

Can you use fewer cards to get to the target number? How did you do that?

Was there a more efficient way of getting to the target number?