Learn Class 8 Math - Playing with Numbers

What is the General Form of Numbers?

For PQ, if the general form is needed, it will look like this:

pq=10p+q

Games with Numbers

Reversing the Digits – Two-Digit Number

Step 1: Let us select any two-digit number ab, which may be written as (10a + b).

Step 2: Its opposite two-digit number can be ba, which may be written as (10b + a).

Step 3: The sum of each of the numbers is ab + ba,

Step 4: By dividing the number by 11, we get eleven (a + b)/11 = (a + b).

Reversing the Digits – Three Digit Number

Step 1: Let's pick any 3 digit quantity ABC, which may be written as (100a + 10b + c).

Step 2: Its opposite quantity can be CBA, which may be written as (100c + 10b + a).

Step 3: By subtracting each of the numbers, i.e. ABC - CBA

Step 4: By dividing the quantity via 99 we get 99 (a-c)/9 = (a-c).

Forming Three-digit Numbers with three digits.

Step 1: Let us take any 3 digit quantity ABC, which may be written as (100a +10b + c).

Step 2: Rearrange the quantity in this type of manner that is bureaucracy specific numbers.

Step 3:By including all of the 3 numbers

Step 4:By dividing the quantity by 37, we usually get the rest zero.

Playing with Numbers Sample Questions for Class 8

Question 1

is equal to :
A. 1
B. 2
C. 689
D. 1023

Question 2

If (12 + 22 + 32 + ..... + 102) = 385, then the value of (22 + 42 + 62 + ..... + 202) is :
A. 770
B. 1155
C. 1540
D. (385 × 385)

Question 3

The value of (112 + 122 + 132 + 142 + ..... + 202) is :
A. 385
B. 2485
C. 2870
D. 3255

Question 4

(475 + 425)2 – 4 × 475 × 425 is equal to :
A. 2500
B. 3160
C. 3500
D. 3600

Question 5

If x is an even number, then x4n, where n is a positive integer, will always have :
A. zero in the unit's place
B. 6 in the unit's place
C. either 0 or 6 in the unit's place
D. None of these