GMAT GYM - Introduction to Multiplication
Multiplication Exercises are available at two levels: Fundamental and Intermediate.
The Fundamental Level contains multiplication questions up to 12 by 12.
The Intermediate Level is slightly more challenging, with multiplication questions up to 20 by 20.
For some of the harder problems, you may wish to apply the properties of multiplication.
For example, to multiply 13 by 18 you can think of 13 as 10 + 3. Instead of multiplying 13 by 18, you would be multiplying (10 + 3) by 18.
= 18 (10 + 3)
= 18 X 10 +18 X 3
= 180 + 54
The strategies you use to eliminate wrong answers in these exercises should help in the GMAT.
For example, when multiplying two numbers, the unitsí digit of the answer will be the of the unitsí digits of the product of the unit digits of the multiplicands.
In the 13 by 18 example above, the unitsí digit of correct answer choice must be a 4, because the product of 3 and 8 is 24, (with unitsí digit of 4).