Question
Plot the integers from -5 to 5 on a number line. Using the number line, compare: (a) and , (b) and , (c) and . Write using inequality symbols.
(NCERT Class 6)
Solution — Step by Step
The number line runs from left to right, with numbers increasing as we move right:
Mark each integer with a dot at equal spacing. Zero sits in the middle. Negative numbers are on the left, positive numbers on the right.
On the number line, is to the left of . A number to the left is always smaller.
is to the left of on the number line. So is smaller.
Among negative numbers, the one with the larger absolute value is actually smaller. , so -4 < -1.
is to the right of . So is greater.
Zero is greater than every negative number and less than every positive number.
Why This Works
The number line gives us a visual way to compare any two numbers. The rule is simple: the number further to the right is always greater. This works for all integers — positive, negative, and zero.
For negative numbers, this might feel counterintuitive at first. is less than even though 100 is “bigger” than 1. Think of it as temperature: is much colder (less) than .
Alternative Method — Using Rules Without a Number Line
- Any positive number > 0 > any negative number
- Between two positive numbers: the bigger one is greater ()
- Between two negative numbers: the one closer to zero is greater ()
For exams, the inequality symbols can be confusing. Think of the symbol as a mouth that always opens towards the bigger number: (mouth opens towards 2) or -3 < 2 (mouth opens towards 2). Both say the same thing.
Common Mistake
Students write because “4 is greater than 1.” This ignores the negative sign. On the number line, is further left (further from zero on the negative side) and is therefore less than . Always think about the number line position, not just the digits.