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(**) Multiplying Two
Numbers Less Than 1000, But Close To 1000:
A.
This method is very similar to section XII and comes from the algebra:
(1000 – a)
(1000 – b) = 1000((1000 – a) – b) + ab
B. Using numbers instead of
variables we get the following:
1.
Find the difference between both the numbers and 1000.
2.
Multiply these two values together and write it down.
Make sure the answer takes up 3 place values.
3.
Subtract the difference found in step 1 of one of the numbers with the
remaining number. Write the result.
Ex [1] 994 x 989 =_________.
a)
1000 – 994 = 6.
b)
1000 – 989 = 11.
c)
6 x 11 = 66. Write 066 to
take up 3 place values.
d)
994 – 11 = 983. Write 983.
(You can also use 989 – 6 = 983)
e)
The answer is 983066.
Ex
[2] 9882 =_________.
a)
1000 – 988 = 12.
b)
12 x 12 = 144. Write 144.
c)
988 – 12 = 976. Write 976.
d)
The answer is 976144.
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