ADDING 3 OR MORE NUMBERS WORKSHEET

1. Add :  -1.5 + 3.5 + 2

2. Add :  5 + (-3) + 7

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 ?

1. Answer :

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

2. Answer :

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

3. Answer :

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.

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