1) Extension Exercise—Balancing Your Account  You just received your bank statement, which shows an end-of-month balance of $25 in your  checking account

1) Extension Exercise—Balancing Your Account 

You just received your bank statement, which shows an end-of-month balance of $25 in your 
checking account. Where did all the money go? You decide to compare last month's deposits 
and withdrawals. A good way to do this is to take the balance from the start of last month. Then 
add a positive number for deposits, and add a negative number for withdrawals. The following 
table shows this process, and the first calculation is completed for you. 

a. Finish filling in the table by showing the calculation needed to obtain the balance after each 
transaction. Place the result of each calculation in the balance column as either a positive or 
negative number. Complete all calculations by hand, and then go back to check your work 
with a calculator. 

b. Observe all the calculations where you added a positive number and a negative number. 

? *If you temporarily ignore the signs of the numbers, then what operation did you actually 
perform on the two numbers in order to obtain the correct balance? 

? *After performing the operation, what about the two numbers determined whether the 
balance was a positive number or a negative number? 

? *In your own words write a general procedure for adding positive and negative numbers. 

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c. Now observe the calculations where you added two numbers with the same sign (either both 
positive or both negative). 

? *If you temporarily ignore the signs of the numbers, then what operation did you actually 
perform on the two numbers? 

? *After performing the operation, what about the two numbers determined whether the 
balance was positive or negative? 

? *In your own words write a general procedure for adding two numbers with the same sign. 

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d. Return to the table and add up all the withdrawals in the second column. Record the sum 
below and in the table (End of Month row, Withdrawal column). 

e. Return to the table and add up all the deposits in the third column. Record the sum below 
and in the table (End of Month row, Deposit column). 

f. Analyze the results of parts d and e. Then explain what is happening to your cash flow over 
this one-month period. 

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g. How did you manage to end up with +25 dollars when more money was going out than 
coming in? 



h. Assuming you have no auto repairs or hair cuts next month, estimate your ending balance for 
next month. Show all your work.