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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