# A lesson on addition and subtraction using calculators

Subject:

Math

2, 3, 4

Summer Jett

Tricia Whitney

GREAT ACTIVITY

Topic: Addition and Subtraction with Calculators

Name of Activities: Nim

Now You’re 21

7 – Up

1 1 Down

2001

Materials Needed: Calculator

2 People

Description of Activity:

NIM – This is a partner activity, so first place everyone with a partner. Have them

punch in the number 21 on their calculators. The two players alternate turns. During

their turn they must subtract 1, 2, or 3 from the number on the calculator. Continue

until one person reaches zero or a negative number. This person is the looser.

VARIATIONS:

Now You’re 21 – Same rules apply as above, except start with zero and add 1, 2, or 3.

First to reach 21 wins.

7 – Up – Same rules apply. Start with zero, add one or two. First to the number seven is the winner.

11 – Down – Same rules apply. Start with eleven, subtract one or two. First to reach zero is the winner.

2001 – Same rules apply, enter 2001, subtract 1 – 99 on each turn. First to reach zero is the winner.

*** This activity can be modified to fit the level that the students are at.

*** You can play the game with other numbers, perhaps start with the number of the

day, birthdays, etc.