Números e Operações Practice Questions

ENEM (Brazil) · ENEM Matemática · 140 free MCQs with instant results and detailed explanations.

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Sample Questions from Números e Operações

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Easy

What is the value of 7 multiplied by 5?

A. 35

B. 40

C. 30

D. 25

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Correct Answer: A

7 multiplied by 5 equals 35, since multiplication combines groups of numbers.

Easy

If a shop sells a shirt for R$100 and offers a 20% discount, what is the sale price of the shirt?

A. R$80

B. R$90

C. R$70

D. R$75

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Correct Answer: A

The sale price is R$80 after applying a 20% discount on R$100, which is a reduction of R$20.

Easy

Which of the following numbers is a prime number?

A. 11

B. 12

C. 15

D. 18

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Correct Answer: A

A prime number is a number greater than 1 that has no positive divisors other than 1 and itself. 11 is prime because it can only be divided by 1 and 11.

Medium

A store sells a shirt for $40 after applying a 20% discount. What was the original price of the shirt?

A. $50

B. $45

C. $55

D. $60

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Correct Answer: A

Let the original price be X. After applying a 20% discount, the shirt is sold for 40, so 80% of the original price is equal to 40. Thus, X = 40 / 0.8 = 50.

Medium

A car travels 150 kilometers at a speed of 75 km/h. How long does the journey take?

A. 2 hours

B. 1.5 hours

C. 3 hours

D. 4 hours

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Correct Answer: A

To find time, use the formula: Time = Distance / Speed. Here, Time = 150 km / 75 km/h = 2 hours.

Medium

What is the result of 45 multiplied by 12?

A. 540

B. 480

C. 600

D. 525

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Correct Answer: A

45 multiplied by 12 equals 540. This can be calculated by performing the multiplication directly or breaking it down (45 * 10 + 45 * 2 = 450 + 90 = 540).

Medium

If a rectangle has a length of 8 cm and a width of 5 cm, what is its area?

A. 40 cm²

B. 30 cm²

C. 50 cm²

D. 45 cm²

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Correct Answer: A

The area of a rectangle is calculated by multiplying its length by its width. Here, 8 cm * 5 cm equals 40 cm².

Hard

If 30% of a number is equal to 45, what is the number?

A. 150

B. 180

C. 200

D. 225

Show Answer & Explanation

Correct Answer: A

Let the number be x. According to the problem, 0.30 * x = 45. Dividing both sides by 0.30, we get x = 45 / 0.30 = 150. Therefore, the correct answer is 150.

Hard

A farmer has a rectangular piece of land with a length of 120 meters and a width of 80 meters. He wants to create a path of uniform width around the entire piece of land, and he wants the total area of the land plus the path to be 10,000 square meters. What should be the width of the path?

A. 5 meters

B. 10 meters

C. 15 meters

D. 20 meters

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Correct Answer: B

The total area of the original land is 120 * 80 = 9600 square meters. To find the path width, let 'x' be the width of the path. The total area becomes (120 + 2x)(80 + 2x) = 10000. Solving gives x = 10 meters.

Q10

Hard

If the function f(x) = 3x^2 - 12x + k has its minimum value at y = -5, what is the value of k?

A. -1

B. -5

C. 1

D. 5

Show Answer & Explanation

Correct Answer: B

The minimum value of a quadratic function occurs at x = -b/2a. Here, a = 3 and b = -12, giving x = 2. Plugging x = 2 back into the function yields f(2) = 3(2^2) - 12(2) + k = -5, leading to k = -5.

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Números e Operações — ENEM (Brazil) ENEM Matemática Practice Questions Online

This page contains 140 practice MCQs for the chapter Números e Operações in ENEM (Brazil) ENEM Matemática. The questions are organized by difficulty — 50 easy, 65 medium, 25 hard — so you can choose the right level for your preparation.

Every question includes a detailed explanation to help you understand the concept, not just memorize answers. Take a timed quiz to simulate exam conditions, or practice at your own pace with no time limit.