# 31 or None

Purpose

This is a level 3 number and algebra strand activity from the Figure It Out series. It relates to Stage 6 of the Number Framework.
A PDF of the student activity is included.

Achievement Objectives
NA3-2: Know basic multiplication and division facts.
NA3-6: Record and interpret additive and simple multiplicative strategies, using words, diagrams, and symbols, with an understanding of equality.
NA3-2: Know basic multiplication and division facts.
Student Activity

Click on the image to enlarge it. Click again to close. Download PDF (174 KB)

Specific Learning Outcomes

use basic facts to solve equations

Required Resource Materials
Digit cards (0-9) for each player (see Related Resources)

FIO, Level 2-3, Basic Facts, 31 or None, page 4

At least 2 classmates to play with

Activity

#### Game

This activity is based on an ancient Chinese game in which players had to make given totals by using four single-digit numbers and the four operations. Thirty-one is a good target as there are many ways in which students can reach this score. Students could use a tally sheet to record who has the highest score in each round.
After students have played the game several times, the target number can be changed. Students may wish to describe why it is easier to get a target of 31 than a target of 13. Similarly, they can be given a target total such as 27 and asked to write as many four-digit combinations for it as they can.
For example:

Where students use different types of calculators, particularly scientific and four-function, the issue of order for operations may arise. For example, given 4 + 6 x 3 – 5 = , a scientific calculator will get 17 whereas a four-function calculator will get 25. Four-function calculators perform calculations in the order of keying, that is, 4 + 6 = 10, then 10 x 3 = 30, and then 30 – 5 = 25.
A scientific calculator uses the convention for operations, that is, multiplication and division are calculated before addition and subtraction. With 4 + 6 x 3 – 5 = , the 6 x 3 = 18 is performed first, and then 4 is added and 5 subtracted: 18 + 4 – 5 = 17.

#### Activity

Students will need to approach this systematically. A table would be useful.