How to multiply integers

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Algebra › How to multiply integers

Questions 1 - 10

1

A plane flies at a rate of 210mi/h. If the plane has flown for five hours, how many miles has it traveled?

1050mi

42mi

215mi

840mi

1000mi

Explanation

Multiply the rate of travel (210 mi/hr) by the time traveled (5 hours), and you get the total distance, 1050 miles.

distance = rate * time

distance = (210mi/hr)(5hr)

distance = 1050mi

2

Simplify the radical.

$\small \sqrt{128}$

$\small 8\sqrt2$

$\small 4\sqrt2$

$\small 4\sqrt{32}$

$\small 8\sqrt{132}$

Cannot be simplified further.

Explanation

$\small \sqrt{128}$

Find the factors of 128 to simplify the term.

$\small 64*2=128$

We can rewrite the expression as the square roots of these factors.

$\sqrt{128}=\sqrt{64}*\sqrt{2}$

Simplify.

$\sqrt{64}*\sqrt{2}=8\sqrt{2}$

3

Evaluate 5x + 3y when x = 7 and y = 9.

62

66

–62

8

–66

Explanation

Plug in 7 for x and 5 for y, giving you 5(7) + 3(9). This is equal to 35 + 27, which equals 62.

5x + 3y

5(7) + 3(9)

35 + 27 = 62

4

Simplify the radical.

$\small \sqrt{50}$

$\small 5\sqrt2$

$\small 10$

$\small 25\sqrt2$

$\small 5$

Explanation

$\small \sqrt{50}$

Start by finding factors for the radical term.

$\small 25*2=50$

We can rewrite the radical using these factors.

$\small \sqrt{25}*\sqrt{2}=\sqrt{50}$

Simplify the first term.

$5*\sqrt{2}=5\sqrt{2}$

5

Rewrite as a number in base ten: $231_{\textrm{six}}$

Explanation

$231_{\textrm{six}}$

$= 2 \cdot 6^{2} + 3 \cdot 6^{1} + 1$

$= 2 \cdot 36 + 3 \cdot 6 + 1$

6

Explanation

When multiplying two negative numbers, the answer is positive. Then multiply normally. Answer is .

7

Explanation

When multiplying two negative numbers, the answer is positive. Then multiply normally. Answer is .

8

Multiply the following numbers: $59\times 9$

Explanation

Multiply the ones digits.

$9\times 9 =81$

The tens digit is eight, which is the carryover.

Multiply the tens digit of the first number with the ones digit of the second number.

$5\times 9 +8 = 45+8 =53$

Combine the numbers with the ones digit of the first calculation.

The answer is:

9

Multiply fifteen with eight.

Explanation

Write the expression to express the question.

$15 \times 8$

Multiply the ones digits.

$5\times 8=40$

Since this number has a tens digit, it will be used as a carryover.

Multiply the tens digits and add the carryover.

$1\times 8 +4 = 12$

Combine the numbers.

The answer is:

10

Multiply: $587 \times 8$

Explanation

Multiply the ones digit of 587 with the eight.

$7 \times 8 = 56$

The tens place is the carryover.

Multiply the tens digit of 587 with the eight and add the carryover.

$8\times 8+5 = 69$

The tens place is the carryover.

Multiply the hundreds digit of 587 with the eight and add the carryover.

$5\times 8+6 = 46$

Combine this number with the ones digits in the other calculations.

The answer is:

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