WAVES WORKSHEET CLASS 9 WITH SOLUTIONS

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How to write algebraic expressions | Operations with Integers Basics ( + - * ÷ )

In this lecture we understand how to write an algebraic expression. We also revise rules for rules for adding/subtracting/multiplying/dividing integers. We learn how to translate words into algebraic expressions. This will help you to write algebraic expressions while doing word problems.

I have attached herewith a worksheet for practice.(Clickhere)

 DIVISIBILITY RULES

 

 Here are Divisibility rules for your reference:

 A number is divisible by

TWO:  if last digit is 0, 2, 4, 6, or 8

THREE: if the sum of the digits is divisible by 3

FOUR : if the last two digits is divisible by 4

FIVE: if the last digit is 0 or 5

SIX:  if the number is divisible by 2 and 3

SEVEN : Cross off the last digit - double this digit and subtract it from the number that remains. {If required, keep doing it till you get a small number.} If the number is divisible by 7, the original number is divisible by 7 .

This one's trick; so here's an example.

i) Consider: 2275 

Last digit is 5 - double this i.e. 10. Subtract 10 from 227. Ans = 217 

Now 217 is divisible by 7 - so 2275 is divisible by 7.

ii) Consider 15925

Last digit is 5 - double this i.e. 10. Subtract 10 from 1592. Ans = 1582

Last digit is 2 - double this i.e. 4.  Subtract 4 from 158. Ans = 154

154 is divisible by 7 - so 15925 is divisible by 7.

 

EIGHT : if last 3 digits is divisible by 8

NINE: if the sum of the digits is divisible by 9

TEN: if the last digit is 0

ELEVEN: Subtract the last digit from the number formed by the remaining digits. If new number is divisible by 11, the original number is divisible by 11

TWELVE:  if the number is divisible by 3 and 4