Question

Which of these is the least four-digit number?
a) 9999
b) 900
c) 9000
d) 1000

Answer 1

Hint: Here in this question, we have to determine which is the least 4 digit number and we have to write the solution which is present in the options. We should know about the numbers and by knowing the place value system and we determine the number. By using the numbers 0, 1, 2, 3, 4, 5, 6, 7, 8 and 9.

Complete step-by-step solution:
In mathematics we have different kinds of numbers namely, natural numbers, whole numbers, integers, rational numbers, irrational numbers and real numbers.
Natural numbers are defined as counting numbers.
Whole numbers are defined as the counting numbers and along with it 0.
Integers are defined as positive and negative numbers of whole numbers.
Rational numbers are defined as the numbers is in the form of \[\dfrac{p}{q}\]
Irrational numbers are defined as the numbers which are not rational.
Real numbers are defined as the combination of integers and rational numbers.
The place value system for 4 digits is defined by

Thousand	Hundred	ten	ones
1000	100	10	1

The second option is incorrect because it is a 3 digit number. As in the question, it is mentioned clearly that the number is 4 digit number
The first option is 9999 where every place value has the number 9, which is the greatest number. The 9999 is the greatest 4 digit number. Therefore the option a is also the wrong one.
Now the option c and option d is left out. On considering option c and option d the unit, tens, hundred places is 0. But the thousand place value is 9 in option c, but in option d, the thousand place value is 1. When we compare these 2 numbers 1 is the least.
Therefore the least 4 digit number is 1000
Thus the correct answer is option ‘c’.

Note: In mathematics we have different kinds of numbers, here while writing the number we choose the numbers which belong to the whole numbers, here we can’t take the numbers from the natural numbers because the natural numbers does not include 0. While writing the digits we need the number 0.