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a formula for computing multiplication of numbers close to 100 Quantitative

eg: 87 * 94
94 is 6 less than 100
87 is 13 less than 100.
so 1st two digits are 87 - 6 = 79
last two digits are 13 * 6 = 78
therefore answer is 7978.
hope it is useful for us in the upcoming CAT.
Cheers, [smiley] [smiley] [smiley]
Prashanth
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this is much less a reply and more a question.
can anyone give me a link which has online quant papers for the cat and is a free website. pagalguy had some but i cant seem to find it anymore.

if u do could u please email me the link instead of posting it.
email is salil_pawah@yahoo.co.in

thanks again.
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Squaring a 2-digit number beginning with 5
Take a 2-digit number beginning with 5.
Square the first digit.
Add this number to the second number to find the first part of the answer.
Square the second digit: this is the last part of the answer.
Example:
If the number is 58...
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Squaring a 2-digit number beginning with 1
Take a 2-digit number beginning with 1.
Square the second digit
(keep the carry) _ _ X
Multiply the second digit by 2 and
add the carry (keep the carry) _ X _
The first digit is one
(plus the carry) X _ _
Example:<...
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I came across these formulae in some Book.Anyways I dont find it of much help.They end up confusing you most of the times.After going round and round u end up doing the same S*** multiplication.
Multiplication of 2 or 3 digit nos. is ok.It helps in case u r in deep S*** when it comes to time.<...
one more to go
MULTIPLICATION FROM 13 TO 19:
The reason why the rule is different for multiplication by 11 and by 12 is obviously because the right digits are different. The right digit, we could call the Parent Index Number (PIN). Thus in 11, the PIN is 1 and in 12 it is 2. (In 13, it ...
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hey guyz,i am loading a few more formulae.
moderators i dont know whether this is redundant stuff .in case if it is i am sorry.
1. Special method for multiplication by numbers from 11 to 19.
Multiplication by 11
Rule: 1. Prefix a zero to the multiplicand
2. Write dow...
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