ADDING 3 OR MORE NUMBERS WORKSHEET

Problem 1 :

Add :  -1.5 + 3.5 + 2

Solution :

Step 1 :

According to the associative property of addition, we can add any two numbers among the given three numbers. 

Then, we have 

(-1.5) + 3.5 + 2  =  (-1.5 + 3.5) + 2  ------(1)

Step 2 : 

In (-1.5 + 3.5), the two numbers have different signs. 

So, find the absolute difference of them without the actual signs. 

|1.5 - 3.5|  =  |-2|  =  2

Step 3 : 

In the two numbers 1.5 and 3.5, the sign of the bigger number is positive. So, we have to take positive sign to the result. 

(1) ----->  -1.5 + 3.5 + 2  =  (+2) + 2

-1.5 + 3.5 + 2  =  4

Problem 2 :

Add :  5 + (-3) + 7

Solution :

Step 1 :

According to the associative property of addition, we can add any two numbers among the given three numbers. 

Then, we have 

5 + (-3) + 7  =  [(5 + (-3)] + 2  ------(1)

Step 2 : 

In [(5 + (-3)], the two numbers have different signs. 

So, find the absolute difference of them without the actual signs. 

|5 - 3|  =  |2|  =  2

Step 3 : 

In the two numbers 5 and 3, the sign of the bigger number is positive. So, we have to take positive sign to the result. 

(1) ----->  5 + (-3) + 7  =  [+2] + 2

5 + (-3) + 7  =  4

Problem 3 :

Tina spent $5.25 on craft supplies to make friendship bracelets. She made $6.75 and spent an additional $3.25 for supplies on Monday. On Tuesday, she sold an additional $4.50 worth of bracelets. What was Tina’s overall profit or loss ?

Solution :

Step 1 :

Use negative numbers to represent the amount Tina spent and positive numbers to represent the money Tina earned.

Step 2 : 

Find -5.25 + 6.75 + (-3.25) + 4.50.

Step 3 : 

Group numbers with the same sign.

-5.25 + (-3.25) + 6.75 + 4.50 ----> Commutative property

(-5.25 + (-3.25)) + (6.75 + 4.50) ----> Associative property

Step 4 : 

Add the numbers inside the parentheses.

-8.50 + 11.25

Find the difference of the absolute values :

|11.25 - 8.50|  =  |2.75|  =  2.75 

In 8.50 and 11.25, the sign of the greater number is positive. So, the result also must be positive and it is 2.75.

Hence, Tina earned a profit of $2.75.

Problem 4 :

In an equestrian event Marcus came first, winning $2300 Megan came second winning $1250.

a) What was the difference between the prizes ?

b) If their scores had been equal, they would have shared the total prize money for first and second. How much would they have each received ?

Solution :

Winning amount of first prize = $2300

Winning amount of second prize = $1250

a) difference between the prizes = 2300 - 1250

= 1050

b) Total amount = 2300 + 1250

= 3550

Winning amount of first prize = second prize

Amount each will receive = 3550/2

= 1775

Problem 5 :

Alysia stands on some scales with 15 kg dumbbell in each hand. If the scales read 92 kg, what does she weigh ?

Solution :

In each hand, she carries 15 kg dumbbell.

Total weight of dumbbell = 2(15)

= 30 kg

Weight measured in scale = 92 kg

Weight of Alysia + weight of dumbbell = 92

Weight of Alysia + 30 = 92

Weight of Alysia = 92 - 30

= 62 kg

So, weight of Alysia is 62 kg.

Problem 6 :

My bank account balance was $1080. I withdrew amounts of $427 and $173. I then banked my pay cheque of $769. What is my bank balance now ?

Solution :

Bank balance = $1080

Withdrawal amounts are $427 and 173

Amount investing with cheque = $769

Withdrawal amount should be subtracted and cheque amount will be added.

= 1080 - (427 + 173) + 769

= 1080 - 600 + 769

= 1849 - 600

= 1249

So, the bank balance amount now is $1249.

Problem 7 :

A woman has $350 in her purse. She gives $22 to each of her five children. How much money does she have left ?

Solution :

Amount the woman has in her purse = $350

Amount given for 5 children = 5(22)

= 110

Amount she have left = 350 - 110

= 240

Problem 8 :

My bank account contains $227 and my fortnightly pay of $540 is added directly into my bank account. If there are no withdrawals, what is my bank balance after 12 weeks ?

Solution :

Original amount she has = $227

fortnightly = 2 weeks

Amount pays for 2 weeks = 540

Amount pays for 12 weeks = 540(6)

= 3240

Total balance for 12 weeks = 227 + 3240

= $3467

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