Helpful Hacks for Math Test Takers
As complex and mysterious math may seem for those lost in a forest of equations, formulas, and figures, take comfort in knowing math may have started with just the use of our ten fingers. That may be cold comfort for you if you’re preparing for a math test. Yet, you are not alone. Many have gone before you.
Those fingers of yours may be used for more than just counting to 10. Our hands can offer shortcuts to multiplication! Other hacks have been used successfully in math tests because they make the complex more simple. Just for fun, let’s visit some shortcuts and hacks which pull us out of the forest so we can see the trees:
Multiplying 6, 7, 8, and 9 just using your hands. Spread the fingers of each hand as wide as you can. Now turn your spread hands vertically so the palms face you, and the fingers on one hand almost touching the fingers of the other hand. According to Instructables.com, you should ascribe the pinky with number 6, then climb up the hand with each finger ascribed to the next number in order. So, each pinky is 6, and each thumb will be a number 10.
When multiplying any of the numbers between 6 and 9, just touch the tips of those numbered fingers together. Count the touching fingers and any fingers below those touching fingers. (Don’t add their ascribed value, just add the number of fingers). The total number of these lower fingers will be the figure in the “tens” place of your multiplication answer.
Next MULTIPLY the number of fingers above the touching finger on your left hand with the number of fingers above the touching finger on your right hand. This product will be the number in the “ones” column in your answer. Try it! Example: If you are asked to multiply 7 x 8: The finger ascribed to 7 in your left hand must touch the tip of the finger ascribed to 8 in your right hand. Counting these fingers and all fingers below them equal 5. So, the number 5 shall sit in the tens column of your multiplication answer. Next, multiply the number of fingers above in your left hand (2) with the number of fingers above your touching finger in your right hand (3). This product of 6 shall sit in the ones column of your multiplication answer. 7 x 8 = 56.
When asked to find percentages of three digit numbers (ex. 30% of 500) use this hack:
Drop the last digit of each side and multiply them together (3 x 50 = 150).
Multiplying by Nines
Here is a hack for testing the multiplication of nines. The product of 9 times each number through 10, starts with zero in the tens column, and 9 in the ones column; then progresses up through each sequential number up in the tens column; and cascades down from 9 in the ones column. (Ex. 9×1=09; 9×2=18; 9×3=27 etc..)
Get the Fraction of Whole Numbers
If you are tested on the fraction of a whole number, try this hack. Divide the whole number by the denominator of the fraction. Take this quotient and multiply it by the numerator of the fraction. (Ex. ¾ of 24 can be calculated by dividing 24 by 4, which equals 6. Then take that 6 and multiply it by the numerator 3, which answers the question as 18!
If Only We Had 11 Fingers
Multiplying by 11 is easy if by single digits. But what about double digits? It’s a split decision. Take the number you are multiplying by 11 then split the digits so that you can insert another digit between them. Get that other digit by adding the two numbers you split together. Your sum is inserted between the split digits to create a new three-digit answer! Ex. 42 x 11: Split the 4 and 2. Add 4 + 2 = 6. Now insert the 6 between them. (462)
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