2. Space Invaders Unit 1 Activity 2

3. Aliens = 539 First shot – 9 Aliens left = 530 Second shot - 30Aliens left = 500 Third shot - 500Aliens left = 0

4. Game 1 Choose a two-digit number and ‘shoot’ the aliens down one at a time using subtraction. Record your moves carefully. Choose some other numbers and repeat. Choose another two-digit number and try again using addition. Your final number should be 100.

5. Game 2 Choose a 3, 4 or 5-digit number and repeat Game 1. Shoot down the digits by working from right to left. Try again shooting them down from left to right. When you are using addition with the 3 digits the final number should be 1000; For 4 digits it should be 10,000. Remember to record your moves carefully.

6. Investigation 1 Your ‘alien’ number is 724.63 Shoot it down using subtraction and starting with the 3 Record your moves Try again using addition You final number should be 1000 Find some other ways of shooting down 724.63

7. Investigation 2 Choose a decimal number of your own with at least 6 digits and 2 decimal places Shoot it down in exactly 4 moves using subtraction. Record your moves Find some other ways of shooting down your number. Repeat using other numbers.