Managing time is just as important as knowing the equations on this section because you have a little less than one minute for each question. That’s why you need to use arithmetic shortcuts to solve questions quickly and correctly.
Here’s a sampling of what you’ll need to know for the ISEE quantitative reasoning section. But, if you really want to ace this section, it will be best to work with a private tutor. Your tutor will walk you through practice questions and help you find the best ways to solve them – a rare advantage most students won’t get.
Practice without a calculator: Because you won’t be given one on the test.
Divisibility: Which of the following integers divides into both 200 and 150?
A. 3
B. 7
C. 30
D. 50
E. 300
Divisibility rules state that numbers divisible by roots of 5 end only in 5 or 0. Both 200 and 150 end in 0; so you know the answer has to be a root of 5. Also, look for patterns like how 200-150=50. So, now that you think the answer is 50, see if it checks out by dividing 200 and 150 by 50. In this case, it does.
Multiplication: Consider this question: -3 x 5 = ? Don’t pay attention to negatives or positives at first, and just multiply the numbers to get 15. Then, apply these multiplication shortcuts to determine the answer has to be negative:
Positive x Positive = Positive
Negative x Negative = Positive
Negative x Positive = Negative
Odds and Evens: All you need to remember here is that even/odd numbers are always two apart in a set. Consider this set: (1,2,3,4,5,6,7,8) The even numbers are 2,4,6,8 (or two apart). The odd numbers are 1,3,5,7 (also two apart). Consider the following question:
If R is an odd integer, what are the next two consecutive odd integers?
A) T and V
B) R and R+1
C) R+1 and R+2
D) R+2 and R+4
E) R+1 and R+3
Correct answer is D because odd/even integers are always two apart in a set.
Prime numbers: Are divisible only by themselves and 1. They are ALWAYS odd numbers, except for 2. Remember that 1 is not a prime number, and the first prime numbers are: (2, 3, 5, 7, 11, 13, 17, 19, 23, 29). On the test, you’ll need to be able to create prime factorization of numbers (dividing numbers into their prime numbers). Take the number 24, and see what prime numbers you can multiply to equal 24. The only way to do this is 2 x 2 x 2 x 3 or 23 × 3. Use prime factorization to answer this question If xy = 13 and both x and y are positive integers, then what is the sum of x + y?
A. 13
B. 14
C. 16
D. 20
E. 26
13 is a prime number; so the only prime factorization is 13 x 1. 13 +1 = 14 (answer choice B).
Percents: Can be tricky. But, use this simple equation: Part x 100 / Total. Consider this question: If Wendy missed 12 out of 80 exam questions, what is the percent of questions she missed? Simply multiply 12 x 100 = 1,200. Then, divide that by 80 = 15 (15% is your answer).
You’ll also see questions like: What’s 20% of 53? To figure these out, slide the decimal point over two places to the left. So 20.0 becomes 0.2. Then, multiply the decimal percentage by the number (0.2 x 53 = 10.6).
Consider another type of question: 5 is what percent of 2? To answer this, you need to turn it into an algebraic equation (5 = n x 2). Then, just solve (n = 5/2 = 2.5). Next, you have to turn 2.5 into a percent by moving the decimal over two places to the left (250%).
Averages: Are actually very simple questions: Jenna’s last four test scores were 35, 56, 75, and 28. What is the average of Jenna’s test scores? All you have to do is add her test scores up and divide by the total number of tests she took. When you add her four test scores up you get 194; then divide that by the total (4) to get 48.5
Varsity Tutors is always available to give you what you need to boost your ISEE score. Contact us today to see if a private ISEE tutor is right for you and your child. Or, see more information on the ISEE and ISEE Verbal Reasoning.
