SUBTRACT WHOLE NUMBERS
SUBTRACT DECIMALS

PROBLEMS

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 1 1. Subtraction by compensating
824
− 358
466

1.  .  a)   How do we compensate for adding 10 ones to 4 ones?

Add 1 ten to 5 tens.

1.  .  b)   Why does that compensate?

Because 1 ten is equal to 10 ones. And if we add the same number to both the larger and the smaller, their difference does not change.

1.  .  b)   How do we compensate for adding 10 tens to 2 tens on top?

Add 1 hundred to 3 hundreds on the bottom.

1.  .  b)   Why does that compensate?

Because 1 hundred is equal to 10 tens.

12.   What do we obtain if we add the difference and the smaller number?

larger
− smaller
difference

The larger number.

1 3.  Under what conditions will the difference

 1 3. a)   be equal to the smaller number?   (Consider an example.)

When the larger number is twice the smaller number.

 1 3. b)   be less than the smaller number?   (Consider an example.)

When the larger number is less than twice
the smaller number.

 1 3. c)   be more than the smaller number?

When the larger number is more than twice
the smaller number.

14.   Subtract.

14.     a)   9238             b)   3420               c)   6806               d)   5000
14.   a) - 2564             b) - 2514               c) - 1739               d) - 3614
14.   6674 906 5067 1386
14.     e)   90.02            f)   43.21               g)   4026.09           h)   90.00
14.   e)  -94.56            f) - 12.34                g) -  280.60            h) -  9.92
14.   85.46 30.87 3745.49 80.08

15.  Alignment

a)  7.02 − 5.68 = 1.34   b)  19.68 − 4 = 15.68
 
c)  2 − .036 = 1.964   d)  23.1 − 4 = 19.1
 
e)  786.5 − .042 = 786.458   f)  15 − 2.048 = 12.952
 
g)  6 − 3.79 = 2.21   h)  8.756 − 3 = 5.756
 
i)  .0974 − .0069 = .0905    

16.  Subtract  6.53  from  22.1.   15.57

17.  What number must you add to one thousand nine to get five
10.  thousand six hundred twelve?

5,612 − 1009 = 4,603

18.  Richard bought a pen for $1.80, a book for $8.50, and he paid with a
17. $20 bill.  How much was his change?  $9.70

19.  Janet paid $1,025 for her car, and she sold it for $1,220.  How much
18.  was her profit?   $195

10.  At the beginning of a car trip, the odometer read 59,872.  At the end
10.  of the trip, it read 60,135.  How many miles was the trip?

60,135 − 59,872 = 263 miles

11.  Your checking account has a balance of $241.73, and you write a
11.  check for $42.95.  Then you deposit $57.69, and you write another
11.  check for $85.48.  What is your present balance?   $170.99


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