Number Names and Sense Chapter Notes | Math Olympiad for Class 2 PDF Download

Number

If you wish to distribute 200 chocolates for your birthday among friends, "two hundred" identifies the exact number of chocolates you wish to buy. Number sense is most useful in this situation.
Understanding numbers is very important for all students to solve math problems. Until now, you have been familiar with numbers up to 100. Now, in this article, we will learn about bigger numbers with three digits.

The smallest three-digit number is 100 and the largest is 999.

The idea of "number sense" describes a child's ability to both understand and use numbers in practice. Thus, the knowledge of number system is needed. A number system is a writing system for expressing numbers.
The number system for grade 2 includes numbers up to 3-digit numbers.
The table shows the place values of the three-digit numbers:
How to write the number names of the three-digit numbers. Depending on their values, we place the digits from right to left: first comes the ones place, then the tens place and finally the hundreds place. This order helps us read and write these numbers correctly.
For example, let us take 235:
The expanded representation of the number is as follows: 200 + 30 + 5
Breaking it down: 200 is read as two hundred (consisting of two sets of hundreds).

30 is read as thirty (comprising three sets of tens).
5 is read simply as five (representing five ones).
When these numbers are added up, 235 is the result.
In other words, this sums up to two hundred and thirty-five.

The table below provides some examples of number and their number names: 

Example: A three-digit number has a digit nine in its ten's place and a digit five in its one’s place. The digit present in its hundred’s place is three more than the digit present in its one’s place. Identify the number.
(a) Six hundred and ninety-five
(b) Eight hundred and ninety-five
(c) Nine hundred and sixty-five
(d) Nine hundred and ninety-five
Ans: (b)
Sol: In a three-digit number, the three place values are One’s place, Ten’s place and Hundred’s place.
Digit at one’s place = 5
Digit at ten’s place = 9
The digit present at hundreds place is three more than the number present at ones place = 5 + 3 = 8
Digit at hundred’s place = 8
So, the number is 895 and its number name is eight hundred and ninety-five.
Hence, option (b) is the correct answer.

Odd Numbers

Odd numbers are numbers that cannot be completely divided by 2 which means they always leave a remainder when divided by 2.
Examples of odd numbers include 1, 3, 5, 7, 9, 11, 13 and so on.

Even Numbers

Even numbers are numbers that can be completely divided by 2 without leaving a remainder. In such cases, the remainder is always zero.
Examples of even numbers include 2, 4, 6, 8, 10, 12, 14 and so on.

Numerals

A numeral is a symbol or group of symbols that represents a number. Numerals can be figures, characters or combinations of characters used to denote specific numerical values.

Example: Count the pair of baby socks and write in the number name.

(a) Thirty-five
(b) Thirty-eight
(c) Forty
(d) Forty-four
Ans: (c)
Sol: If we count the number of socks row-wise like in the first row there are 10 socks, in the second row, there are 6 socks and so on. So if we proceed in this manner, we will get our answer as 40.
Therefore, there are forty pairs of socks.
Hence, option (c) is the correct answer.