CLASS III
Mathematics
Numbers
Part B
Successors and
Predecessor
Successor
The number directly after a given number
To find successor of a given whole number, add 1 to given number.
For example: 67+1=68 is the successor of 67.
Predecessor
The number directly before a given number.
To find predecessor of a given number subtract 1 from the given number.
For example: 67-1=66 is the predecessor of 67.
Skip counting
Skip counting can be defined as the method of counting forward by numbers.
To skip count, we keep adding the same number each time to the previous number.
For example: skip counting by 3- 2,5,8,11,14,17,20 etc
Comparison of numbers
Comparing numbers is an important part of the understanding the mathematical concepts of ‘ greater than ‘ and ‘less than’ , and for developing skills for making logical guesses.
We usethese signs to compare numbers:
To remember which way around the "<" and ">" signs go, just remember:
BIG > small
small < BIG
Rules of comparing
numbers
The number/numeral having more digitsis greater For example: 99>9
If two numbers have the same number of digits, we compare them on the basis of their extreme left digits. The number with the greater extreme left digit is greater.
For example: 514 > 298, because 5 > 2
If the extreme left digits of two numbers are the same, we compare them on the basis of the next digits towards their right and so on.
For example:64283 > 63198, because 6 = 6, but 4 > 3
Ascending and descending
order
In ascending order, numbers are arranged from smallest to largest order.
Whereas
In descending order, numbers are arranged fromlargest to smallest Order.
Forming greatest and
smallest numbers
To get the greatest number, arrange the digits in descending order.
For example: The greatest number using the digits 5 7 3 8 is 8753.
To get the smallest number, arrange the digits in ascending order.
For example : The smallest number using the digits 5 7 3 8 is 3578.
Rounding off Numbers
Rounding is a way of simplifying numbers to make them easier to understand or work with. Rounding can be used when
anexact number isn't needed, and an approximate answer will do.
Rules of
rounding off numbers
If the number you are rounding is followed by 5, 6, 7, 8, or 9, round the number up.
For example: 47 rounded to the nearest ten is 50.
If the number you are rounding is followed by 0, 1, 2, 3, or 4, round the number down.
For example: 83 rounded to the nearest ten is 80
What Are You Rounding to?
Numbers can be rounded to the nearest ten, the nearest hundred, the nearest thousand, and so on.
All the numbers to the right of the place you are rounding to become zeros.
For example 4,827.
4,827 rounded to the nearest ten is 4,830
4,827 rounded to the nearest hundred is 4,800
4,827 rounded to the nearest thousand is 5,000
Roman numerals
Till now we have been playing with numbers that are a part of the Hindu-Arabic numeral system. Though it is the most widely used system nowadays, there exists another number system known as the Roman numerals.
The Roman numeral system was commonly used in ancient Rome and European civilizations, who had no idea of the Hindu-Arabic system!
Numbers in this system are represented by combinations of letters from the Latin alphabet.
The Roman symbols
Romans Numerals are based on the following symbols
How To Remember
Think "MeDiCaL XaVIer".
It has the roman numerals in descending order from
1 5 10 50 100 500 1000
I V X L C D M
Rules to write Roman
numerals
When a symbol appears after a larger (or equal) symbol it is added.
For Example: VI = V + I = 5 + 1 = 6
But if the symbol appears before a larger symbol it is subtracted.
For Example: IV = V − I = 5 − 1 = 4
Don't use the same symbol more than three times in a row .
The symbols V, L and D are never repeated.
The symbols V, L and D are never written to the left of a symbol of greater value i.e. V, L and D are never subtracted. The symbol I can be subtracted from V and X only. The symbol X can be subtracted from L, M, and C only.
A symbol cannot be subtracted more than once from a particular symbol of greater value.
Exercise 1:
Skip counting
Exercises 2:
Who am I?
Match with
the number.
Exercise 3:
Rounding off the numbers and Roman numbers
Round the following numbers to the nearest ten.
a: 848 b: 69 c: 191 d:6 e: 918
Round the following numbers to the nearest hundred.
a: 373 b: 944 c: 881 d: 215 e: 506
Write the numbers as Roman numerals a: 38 b: 73 c: 96 d: 57 e: 60
Exercise 4:
Short form and expandable
form
Write the following in the expanded form:
(i) 5371 (ii) 3603 (iii) 1080 (iv) 7091 (v) 6500
Write the following in short form:
(i) 5000 + 300 + 20 + 9 (ii) 2000 + 100 + 3
(iii) 7000 + 30 + 1
(iv) 3000 + 700 + 50 + 1 (v) 2000 + 4
Exercise 5:
Successor and predecessor
Write the successor of the following:
(i) 3099 (ii) 7992 (iii) 5997 (iv) 2000 (v) 8889 (vi) 9089
Write the predecessor of the following:
(i) 3140 (ii) 8030 (iii) 1480 (iv) 4000 (v) 7001 (vi) 1111
Exercise 6:
Even and Odd
Tell whether each number is odd or even.
(i) 6 _____________
(ii) 36 _____________
(iii) 23 _____________
(iv) 74 _____________
(v)54 _____________
(vi) 0 _____________
(vii) 98 _____________
(viii) 952 _____________
Exercise 7 :
Ascending and descending
order
Arrange the following in ascending order:
(i) 3805, 3078, 3870, 2077 (ii) 1395, 1094, 3074, 3019 (iii) 5304, 5096, 5840, 5400 (iv) 8105, 8549, 8269, 8335
Arrange the following in descending order:
(i) 1125, 1252, 2250, 3210 (ii) 3010, 3011, 3101, 3001 (iii) 5215, 6130, 7124, 4251 (iv) 7234, 7432, 7329, 7587
Exercise 8:
Comparing numbers
Compare the following with > or <:
(i) 2005 _____ 2050 (ii) 4810 _____ 4081 (iii) 1010 _____ 1001 (iv) 1048 _____ 1084 (v) 6005 _____ 6050 (vi) 4018 _____ 4810
