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The Other Side of Zero – Class 6 Mathematics notes, important questions and MCQs

NCERT Class 6 Mathematics, chapter 10. Notes, key terms, important questions with answers and MCQs.

Chapter overview

Numbers less than zero are negative numbers. Together with zero and positive numbers they form integers, used for temperatures, floors below ground, and money owed.

Integers

Integers: …, −3, −2, −1, 0, 1, 2, 3, ….
On a number line, numbers increase to the right and decrease to the left.
−5 < −2 because −5 is further left.

Adding and subtracting on a number line

Adding a positive number: move right; adding a negative number: move left.
A number and its opposite add to zero: 4 + (−4) = 0.
Real life: lift buttons (B1, B2), temperatures (−4 °C), bank balance (debt).

Key terms

Integer: positive or negative whole number, or zero
Negative number: number less than zero
Opposite (additive inverse): number that adds with a given number to give zero

Formulas

a + (−a) = 0

Important questions with answers

Write the additive inverse of −15 and of 9.2 marks

Additive inverse of −15 is 15; of 9 is −9 (their sums are 0).

The temperature in Shimla was 5 °C in the afternoon and −4 °C at night. By how many degrees did it fall?3 marks

Fall = 5 − (−4) = 5 + 4 = 9 °C.

In a quiz, +5 is given for a correct answer and −2 for a wrong one. Riya answered 8 correctly and 5 wrongly; Sam answered 6 correctly and 2 wrongly. Find their scores and who won by how much.5 marks

Riya: 8 × 5 + 5 × (−2) = 40 − 10 = 30. Sam: 6 × 5 + 2 × (−2) = 30 − 4 = 26. Riya won by 30 − 26 = 4 marks.

Quick revision

Right on the number line = bigger.
Opposites add to zero.
Below sea level and below zero °C are negative.

Exam tips

Zero is neither positive nor negative.
The smaller of two negative numbers is the one with the bigger digit (−9 < −3).

Practice MCQs

Which is a negative integer?
1. 0
2. −7
3. 5
4. 1/2
Show answer
Answer: (b) −7. Less than zero.
Which is greater, −3 or −8?
1. cannot say
2. −8
3. equal
4. −3
Show answer
Answer: (d) −3. −3 is to the right.
−6 + 4 equals
1. −10
2. −2
3. 2
4. 10
Show answer
Answer: (b) −2. Move 4 right from −6.
The opposite of −9 is
1. −9
2. 9
3. 0
4. 1/9
Show answer
Answer: (b) 9. −9 + 9 = 0.
(−8) + 5 − (−3) equals
1. −6
2. 0
3. 6
4. −16
Show answer
Answer: (b) 0. −8 + 5 + 3.
A lift is at floor 3 and goes down 5 floors. It reaches floor
1. 2
2. −2
3. 8
4. −8
Show answer
Answer: (b) −2. 3 − 5.
Temperature falls from 5 °C to −3 °C. The fall is
1. 2 °C
2. −8 °C
3. 8 °C
4. 3 °C
Show answer
Answer: (c) 8 °C. 5 − (−3).
A lift is at floor +3. It goes down 7 floors and then up 2. Where is it
1. 12
2. 2
3. −4
4. −2
Show answer
Answer: (d) −2. 3 − 7 + 2.

All chapters of Class 6 Mathematics

Written by Kundali IQ from standard, well-established facts to help with revision. This is not an official NCERT publication; always read your textbook too.