The Other Side of Zero — Practice

Q1. The chapter 'The Other Side of Zero' begins by asking: do numbers exist to the left of 0 on the number line, so that the number ray can be completed to a true number line?

• A. Yes, and these numbers are called negative numbers.
• B. No, the number ray cannot be extended to the left of 0.
• C. Yes, but they are called fractions.
• D. No, only 0 lies at the left end of the number line.

Q2. In Bela's Building of Fun, the lift has two buttons. What do '+' and '−' do?

• A. '+' takes the lift up, '−' takes the lift down.
• B. '+' takes the lift down, '−' takes the lift up.
• C. Both '+' and '−' take the lift up; speed differs.
• D. Both buttons open the door; neither moves the lift.

Q3. In Bela's Building of Fun, which floor is called Floor 0?

• A. The topmost floor.
• B. The Welcome Hall on the ground floor.
• C. The lowest floor underground.
• D. The Food Court.

Q4. A number written with a '+' sign in front, such as +3 or +7, is called

• A. A positive number.
• B. A negative number.
• C. A fraction.
• D. An inverse number.

Q5. Which of the following is a negative number?

• A. +8
• B. 0
• C. 12
• D. −5

Q6. How does the chapter describe the number 0?

• A. It is a positive number because it has no '−' sign.
• B. It is a negative number because it lies left of +1.
• C. It is both positive and negative at once.
• D. It is neither positive nor negative.

Q7. In Bela's Building of Fun, which expression describes the meaning of addition with integers?

• A. Starting Floor + Movement = Target Floor.
• B. Target Floor − Movement = Starting Floor.
• C. Movement × Starting Floor = Target Floor.
• D. Target Floor + Starting Floor = Movement.

Q8. Every integer has another number associated with it which, when added to it, gives zero. This other number is called its

• A. Successor.
• B. Predecessor.
• C. Reciprocal.
• D. Additive inverse.

Q9. What is the additive inverse of +3?

• A. +3
• B. 0
• C. +6
• D. −3

Q10. On the integer number line, all negative numbers are

• A. Less than 0.
• B. Greater than 0.
• C. Equal to 0.
• D. Greater than all positive numbers.

Q11. In Bela's Building of Fun, which expression describes the meaning of subtraction with integers?

• A. Target Floor − Starting Floor = Movement needed.
• B. Starting Floor − Target Floor = Movement needed.
• C. Starting Floor + Target Floor = Movement.
• D. Movement − Starting Floor = Target Floor.

Q12. According to the chapter, subtracting a negative number is the same as

• A. Adding the same negative number.
• B. Adding the corresponding positive number.
• C. Multiplying by zero.
• D. Subtracting the corresponding positive number.

Q13. In the token model of the chapter, what does a green token represent?

• A. A positive token, worth +1.
• B. A negative token, worth −1.
• C. A zero pair on its own.
• D. An empty pocket.

Q14. What is a 'zero pair' in the token model?

• A. Two positive tokens grouped together.
• B. Two negative tokens grouped together.
• C. One positive token and one negative token.
• D. Any pair of tokens of the same colour.

Q15. Who gave the first general treatment of positive numbers, negative numbers and zero as equally valid numbers, with explicit rules for arithmetic on them?

• A. Aryabhata, around 500 CE.
• B. Brahmagupta, in 628 CE.
• C. Lazare Carnot, in the 18th century.
• D. Ramanujan, in 1913.