FRAME 1-27.
Solution to
To check an addition problem, simply reverse the order of the addends
Frame 1-26
and add again. For example:
455
Check: 405
473
361
- 50
+ 50
+ 361 is checked in this manner:
+ 473
405
455
834
834
NOTE: When more than two numbers are added together, there is more
than one way to rearrange the addends. The easiest may be to begin
with the bottom and add upward (with the top number being added last).
The term "adding up" comes from an older method in which the sum was
written at the top instead of the bottom.
NOTE: Filling in spaces with zeros can help to keep columns straight.
Solve and check:
34 + 121 + 87.
____________________________________________________________________________
FRAME 1-28.
Solution to
Just as subtraction problems can be checked using addition, so addition
Frame 1-27
problems can be checked using subtraction. Subtracting one addend
from the sum will yield the remaining addend. (This method of checking
242
11
is used less than the reverse adding method.)
34 Check: 034
121
121
Check: 473 + 361 = 834
+ 87
087
11
242
____________________________________________________________________________
FRAME 1-29.
Solution to
Division can be checked by multiplying the quotient (without the
Frame 1-28
remainder) by the divisor and adding the remainder (if any). The resulting
number will be the dividend. For example:
7 13
7 13
834
or
834
5
5
quotient
-473
-361
3/ 17
Check:
x3
divisor
361
473
15
15
2
+2
remainder
17
dividend
Solve and check this problem: 4,864 13.
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MD0900
1-12
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