Easy Steps: Check Math Problems Easily

Question

How do you check your math answer?

Ronitte Libedinsky is an Academic Tutor and the Founder of Brighter Minds SF, a San Francisco, California based company that provides one-on-one and small group tutoring. Specializing in tutoring mathematics (pre-algebra, algebra I/II, geometry, pre-calculus, calculus) and science (chemistry, biology), Ronitte has over 12 years of experience tutoring to middle school, high school, and college students. She also tutors in SSAT, Terra Nova, HSPT, SAT, and ACT test prep. Ronitte holds a BS in Chemistry from the University of California, Berkeley, and an MS in Chemistry from Tel Aviv University.

Ronitte Libedinsky, MS

Academic Tutor

Expert Answer

There are a couple of ways to check your math answer. The easiest way is to plug your solution back into the problem and work backwards to see if you get the right numbers that way. You can also take a look at your answer and see if it makes sense. For example, if you got a very large number for your answer, and you've been working with smaller numbers, you may not have the right solution.

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Question

How do I work out 15% of something?

Donagan

Top Answerer

Convert 15% to 0.15, then multiply it by the number you're working with.

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Question

What is the least number that is divisible by 2,4,5,8 and 10?

Donagan

Top Answerer

It's 40. 40 is 2 x 4 x 5. You don't use 8 or 10 as factors, because they can both be factored into two of the other numbers being considered (8 is 2 x 4, and 10 is 2 x 5).

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Question

3, 10, 19, 30, 42, 58, 75, __ - what's the missing number?

Donagan

Top Answerer

That sequence is neither geometric nor arithmetic, and it shows no other consistent pattern, so the next number cannot be calculated.

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Question

How do I draw 3, 5, 9 on a segment line?

EpcotMagic

Top Answerer

To show 3, 5, and 9 on a number line, you simply place each value at its correct position in increasing order along the line. Start by drawing a horizontal line, mark evenly spaced tick marks, and label them 0, 1, 2, and so on. Then place a point above 3, another above 5, and another above 9, keeping the spacing consistent so the distances reflect their actual values.

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Question

If five DVDs are packaged in plastic wrap, five packages are packed in a box, and five boxes are packed in a crate, how many DVDs are packed in a crate?

EpcotMagic

Top Answerer

To find the number of DVDs in a crate, first calculate the number of DVDs per box by multiplying the number of wrapped DVDs by the number of packages per box (5 x 5 = 25). Then, multiply this result (25) by the number of boxes per crate (5) to find that you have a total of 125 DVDs in a crate.

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Question

How can I understand what a position pattern is?

EpcotMagic

Top Answerer

A position pattern describes how the positions of terms in a sequence change. Instead of focusing on the values themselves, it emphasizes where each term appears and how that position relates to the overall pattern.

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Question

If Catherine uses 80 g of sugar to make 12 muffins, how many muffins can I make with 140 g of sugar?

EpcotMagic

Top Answerer

You can make 21 muffins with 140 g of sugar. To determine this, first calculate the sugar needed per muffin: 80 g / 12 muffins, which is approximately 6.67 g per muffin. Then, divide the available 140 g of sugar by this rate to find the total number of muffins.

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Question

How do I express 225,643 : 68,952 in its simplest ratio form?

Community Answer

That ratio is already in its simplest form. The easiest way to determine that is to use a calculator and divide 225,643 by 68,952. Because the quotient is not an integer (a whole number), the ratio will not reduce to a simpler ratio.

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Question

If 32 students are in a classroom and 12.5% own at least one pet, how many students do not own any pets?

I_l1ke_gam3s

Community Answer

If 12.5% of students own pets, then 87.5% (100% - 12.5%) do not. To find the number of students without pets, calculate 87.5% of 32: 32 * 0.875 = 28. Therefore, 28 students do not own any pets.

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Question

Is 32 evenly divisible by 4?

EpcotMagic

Top Answerer

Yes, 32 is evenly divisible by 4. Since 8 and 4 multiplied together make 32, it's evenly divisible by 4.

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Question

What is the average sale of pens per minute if 40 pens were sold in 15 minutes on Monday and 95 pens in 30 minutes on Tuesday?

EpcotMagic

Top Answerer

To find the average sale of pens per minute, calculate the total pens sold and divide by the total time spent selling. You sold a total of 135 pens (40 + 95) over 45 minutes (15 + 30). Therefore, the average sale rate is 3 pens per minute.

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Question

I bought 25 kg of rice, used 1½ kg on the first day and 4½ kg on the second. How do I calculate the remaining quantity and what operations are involved?

EpcotMagic

Top Answerer

To calculate the remaining quantity, you will first add the amounts of rice used on both days, then subtract this sum from the initial total. For example, adding 1½ kg and 4½ kg results in 6 kg, which you then subtract from 25 kg to get 19 kg of rice.

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Question

How do I check if my calculation of 125.33 - 77.24 + 25.00, resulting in 73.09, is correct?

I_l1ke_gam3s

Community Answer

You can verify the calculation by inputting the full expression into a calculator or by re-performing the steps manually.

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Question

If the chance of rain is 17%, how should I state the probability?

I_l1ke_gam3s

Community Answer

The probability of rain is 17%. In this context, 'chance' and 'probability' are often used interchangeably.

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Question

What is the answer for 4x - 6 when x = 5?

Community Answer

Substitute 5 for x in that expression. (4)(5) - 6 = 20 - 6 = 14.

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Question

What is 50 + 10 x 0 + 7 + 2 ?

I_l1ke_gam3s

Community Answer

Multiply first, then add: 10 x 0 = 0. Then 50 + 0 + 7 + 2 = 59.

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Question

What is 35 ÷ 6?

Community Answer

35 / 6 = 5.833.

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Question

How do I solve 5x+3y=11, and 2x-7y= -12?

I_l1ke_gam3s

Community Answer

These are simultaneous equations. There are several ways to solve them. In this case the easiest way is the elimination method. (See Solve Simultaneous Equations Using Elimination Method. Multiply the first equation by 2 and the second one by -5. You get 10x + 6y = 22, and -10x + 35y = 60. Add the two equations together: 41y = 82, and y = 2. Now plug that y-value into either original equation: 5x + 3(2) = 11. 5x + 6 = 11, and 5x = 5, so x = 1.

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Question

I need to determine the total cost of 7 tarts and 6 cakes, given that 4 tarts and 4 cakes cost $12, and 3 tarts cost as much as 2 cakes.

Community Answer

First, understand that one tart costs two-thirds the price of one cake (since 3 tarts = 2 cakes). Then, convert the initial purchase of 4 tarts and 4 cakes for $12 into an equivalent number of cakes: (4 * 2/3) + 4 = 20/3 cakes' worth. This means one cake costs $12 / (20/3) = $1.80, and thus one tart costs (2/3) * $1.80 = $1.20. Therefore, the total cost for 7 tarts and 6 cakes is (7 * $1.20) + (6 * $1.80) = $8.40 + $10.80 = $19.20.

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Question

How do I convert 0.345 km to meters?

I_l1ke_gam3s

Community Answer

Multiply by 1000. The answer is 345 meters.

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Question

The area of a 24-meter-long rectangular garden is 480sq.m. Find the perimeter of the garden.

Community Answer

First you have to find the width, which is the area divided by the length. 480 sq m / 24 m = 20 m. The perimeter is twice the length plus twice the width: 2(24) + 2(20) = 48 + 40 = 88 meters.

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Question

How do I check my math answer? 3x - 1 = 2x. The answer I get is x=1.

I_l1ke_gam3s

Community Answer

Substitute 1 for x in the original equation. 3(1) - 1 =2(1). So 3 - 1 = 2. That means x does equal 1.

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Question

127.50 + 110.25 = 237.75. How do you check this?

I_l1ke_gam3s

Community Answer

Either do 237.75 - 127.50 or 237.75 - 110.25. If you get the other addend when you subtract, your answer is correct.

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