Pre-Algebra : Pre-Algebra

Study concepts, example questions & explanations for Pre-Algebra

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Example Questions

Example Question #1211 : Pre Algebra

\(\displaystyle 7*6\)

Possible Answers:

\(\displaystyle 42\)

\(\displaystyle 76\)

\(\displaystyle 32\)

\(\displaystyle 48\)

\(\displaystyle 13\)

Correct answer:

\(\displaystyle 42\)

Explanation:

The numbers are positive. We just multiply. Answer is \(\displaystyle 42\)

Example Question #1212 : Pre Algebra

\(\displaystyle -7*0\)

Possible Answers:

\(\displaystyle -1\)

\(\displaystyle 0\)

\(\displaystyle 7\)

\(\displaystyle -7\)

\(\displaystyle 1\)

Correct answer:

\(\displaystyle 0\)

Explanation:

There is a negative number and zero. Regardless whether the number is positive or negative, anything multiplied by zero is always zero. Answer is \(\displaystyle 0\).

Example Question #1213 : Pre Algebra

\(\displaystyle -9*4\)

Possible Answers:

\(\displaystyle 36\)

\(\displaystyle -36\)

\(\displaystyle 12\)

\(\displaystyle -13\)

\(\displaystyle -26\)

Correct answer:

\(\displaystyle -36\)

Explanation:

We have one positive and one negative number.

When multipled, our answer is negative.

The product is \(\displaystyle -36\).

Example Question #194 : Operations And Properties

\(\displaystyle -15*-11\)

Possible Answers:

\(\displaystyle 165\)

\(\displaystyle -26\)

\(\displaystyle 26\)

\(\displaystyle -145\)

\(\displaystyle -165\)

Correct answer:

\(\displaystyle 165\)

Explanation:

We have two negative numbers. When multiplied, the answer is positive.

\(\displaystyle -15\\ \underline{\times -11}\)

          \(\displaystyle 15\)

    \(\displaystyle \underline{+150}\)

        \(\displaystyle 165\)

The product is \(\displaystyle 165\).

Example Question #201 : Operations

\(\displaystyle -4*-7*9\)

Possible Answers:

\(\displaystyle -252\)

\(\displaystyle 252\)

\(\displaystyle -48\)

\(\displaystyle -168\)

\(\displaystyle 256\)

Correct answer:

\(\displaystyle 252\)

Explanation:

We have two negative numbers and one positive number. We multiply from left to right. Two negative numbers multiplied make a positive number. Two positive numbers multiplied is also positive.

\(\displaystyle -4\cdot -7=28\)

Now the expression becomes,

\(\displaystyle 28\cdot 9\)

Answer is \(\displaystyle 252\).

Example Question #202 : Operations

\(\displaystyle -6*-5*-4*3\)

Possible Answers:

\(\displaystyle 120\)

\(\displaystyle -360\)

\(\displaystyle -480\)

\(\displaystyle -240\)

\(\displaystyle 360\)

Correct answer:

\(\displaystyle -360\)

Explanation:

We have three negative numbers and one positive number. We multiply from left to right. Two negative numbers multiplied makes a positie number. However, that positive number multiplied by a negative number is a negative number. The same applied when multipled with a positive number.

\(\displaystyle -6\cdot -5=30\)

Now our expression becomes,

\(\displaystyle 30\cdot -4\cdot 3\)

\(\displaystyle 30\cdot -4=-120\).

Finally the expression becomes,

\(\displaystyle -120\cdot 3=-360\).

Our answer is \(\displaystyle -360\).

Example Question #1214 : Pre Algebra

\(\displaystyle 95\div 19\)

Possible Answers:

\(\displaystyle 5\)

\(\displaystyle 15\)

\(\displaystyle 3\)

\(\displaystyle 11\)

\(\displaystyle 4\)

Correct answer:

\(\displaystyle 5\)

Explanation:

The numbers are positive. We just divide.

\(\displaystyle \frac{95}{19}=\frac{5\cdot 19}{19}=5\)

Answer is \(\displaystyle 5\)

Example Question #1215 : Pre Algebra

\(\displaystyle -24\div 6\)

Possible Answers:

\(\displaystyle 4\)

\(\displaystyle 6\)

\(\displaystyle 3\)

\(\displaystyle -2\)

\(\displaystyle -4\)

Correct answer:

\(\displaystyle -4\)

Explanation:

We have one positive and one negative number. When divided, our answer is negative.

\(\displaystyle \frac{-24}{6}=\frac{-4\cdot 6}{6}=-4\)

The quotient is \(\displaystyle -4\).

Example Question #1216 : Pre Algebra

\(\displaystyle -204\div -12\)

Possible Answers:

\(\displaystyle -13\)

\(\displaystyle -17\)

\(\displaystyle 17\)

\(\displaystyle 14\)

\(\displaystyle 27\)

Correct answer:

\(\displaystyle 17\)

Explanation:

We have two negative numbers. When divided, the answer is positive.

\(\displaystyle \frac{-204}{-12}=\frac{-12\cdot 17}{-12}=17\)

The quotient is \(\displaystyle 17\).

Example Question #206 : Operations

\(\displaystyle 400\div -20\div 10\)

Possible Answers:

\(\displaystyle -2\)

\(\displaystyle 2\)

\(\displaystyle -5\)

\(\displaystyle -1\)

\(\displaystyle 4\)

Correct answer:

\(\displaystyle -2\)

Explanation:

We have two positive numbers and one negative number. We  work from left to right. When a positive number is divided by a negative number, the answer is a negative number. The same applied when divided by a positive number.

\(\displaystyle \frac{400}{-20}=\frac{20\cdot 20}{-20}=-20\)

Now the expression becomes,

\(\displaystyle -20\div10\)

\(\displaystyle \frac{-20}{10}=\frac{-2\cdot 10}{10}=-2\).

Answer is \(\displaystyle -2\).

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